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(Hypertension. 1996;27:704-708.)
© 1996 American Heart Association, Inc.

Articles

Myocardial Contractility Is Modulated by Angiotensin II via Nitric Oxide

H. Gómez Llambí; F. Manni; P. La Padula; O.A. Carretero; C.M. Taquini

From Ininca, University of Buenos Aires (Argentina); and the Henry Ford Hospital, Detroit, Mich (O.A.C.).

Correspondence to Oscar A. Carretero, MD, Hypertension and Vascular Research Division, Henry Ford Hospital, 2799 W Grand Blvd, Detroit, MI 48202-2689.

	Abstract

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Abstract We hypothesized that in cardiac muscles, angiotensin II partially inhibits the contractile response to ß-agonists. We studied the contractile response of isolated rat left ventricular papillary muscles to isoproterenol and the effect of angiotensin II on this response. We also investigated whether the effect of angiotensin II is mediated by bradykinin, prostaglandins, nitric oxide, and/or cGMP. Contractility of isolated papillary muscles was recorded with a force transducer, and rest tension, maximal developed tension (DT), maximal rate of rise in developed tension [T⁽⁺⁾], and maximal velocity of relaxation [T^(-)] were measured (1) under basal conditions, (2) after pretreatment with various drugs, and (3) after cumulative doses of isoproterenol. Pretreatment groups included (1) vehicle (controls); (2) angiotensin II; (3) angiotensin II and N-nitro-L-arginine, an inhibitor of nitric oxide release; (4) L-arginine, the substrate for nitric oxide synthase; (5) L-arginine and N-nitro-L-arginine; (6) 8-bromo-cGMP, analogous to the second messenger of nitric oxide; (7) angiotensin II and icatibant (Hoe 140), a bradykinin B₂ antagonist; and (8) angiotensin II and indomethacin, a cyclooxygenase inhibitor. There were no differences in contractile parameters before and after any of the pretreatments. Isoproterenol increased DT, T⁽⁺⁾, and T^(-), and these effects were attenuated by angiotensin II, L-arginine, and 8-bromo-cGMP. The effects of angiotensin II and L-arginine were blocked by inhibition of nitric oxide release with N-nitro-L-arginine. Neither the bradykinin B₂ antagonist nor the cyclooxygenase inhibitor altered the effects of angiotensin II. We concluded that angiotensin II partially inhibits the contractile response of cardiac papillary muscles to isoproterenol. This effect is likely mediated by nitric oxide release, perhaps acting via cGMP. Kinins and prostaglandins do not appear to participate in the inhibitory effect of angiotensin II. Attenuation of the contractile effect of isoproterenol by angiotensin II may help explain why cardiac function improves in heart failure after blockade of the renin-angiotensin system.

Key Words: angiotensin II • isoproterenol • kinins • nitric oxide • myocardial contraction • L-NA

	Introduction

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Kinins, Ang II, NO, and prostaglandins are released in the heart, where they may play an important role as paracrine hormones regulating not only coronary blood flow but also cardiac function.¹ Using rat sarcolemmal membranes, Anand-Srivastava² has shown that Ang II and the ß-adrenergic system are negatively coupled in the heart. Seyedi et al³ reported that in microvessels and large arteries from the dog heart, Ang II stimulates the formation of NO via local kinin production. In several tissues NO stimulates soluble guanylate cyclase and increases intracellular levels of cGMP, thereby reducing intracellular calcium levels and contractility.^{4 5} Furthermore, NO inhibits the cardiac contractile response to ß-adrenergic stimulation in rat cultured myocardial cells.^{6 7} These observations suggest interactions among kinins, NO, cGMP, the renin-angiotensin system, and the ß-adrenergic response.

We hypothesized that in cardiac muscles, Ang II partially inhibits the contractile response to ß-agonists. Since preliminary studies showed that the contractile response to isoproterenol was partially blocked by Ang II, we further hypothesized that the effect of Ang II is mediated by the release of NO or prostaglandins, either directly or via kinins. To test this hypothesis, we determined whether the contractile response of isolated rat left ventricular papillary muscles to isoproterenol is inhibited in part by Ang II, L-Arg (the precursor of NO), or 8-Br-cGMP, an analogue of cGMP that is one of the second messengers of NO. We also studied whether the effect of Ang II is blocked by inhibition of NO release, a kinin antagonist, or a cyclooxygenase inhibitor. We used isolated papillary muscles to avoid the increased sympathetic nervous activity caused by Ang II, since such an increase by itself would elevate the chronotropic and inotropic activity of the heart.

	Methods

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Male Wistar rats weighing 280 g were given access to standard dry meal and water ad libitum. After sodium pentobarbital anesthesia (40 mg/kg IP), the heart was rapidly removed and placed in oxygenated Ringer's solution. The papillary muscle was dissected from the left ventricle and mounted vertically in a chamber containing Ringer's solution of the following composition (mmol/L): NaCl 128.3, KCl 4.7, CaCl 1.35, NaHCO₃ 20.23, NaH₂PO₄ 0.35, MgSO₄ 1.05, and glucose 11. When isoproterenol was used, the solution also contained EDTA (0.045 mmol/L) and ascorbic acid (0.11 mmol/L). The solution was equilibrated with a mixture of 5% CO₂ and 95% O₂ with pH and temperature kept constant at 7.4 and 29°C, respectively. Isometric mechanograms were recorded on a Beckman R511A with a Statham force transducer and 9853 coupler (Gould-Statham), and the first derivative of developed tension was obtained with a 9879 dP/dt coupler (Gould-Statham). Rectangular pulses of 10 milliseconds duration with an amplitude 20% higher than the threshold of each preparation were delivered with a Grass stimulator. Contraction frequency was kept constant at 12 beats per minute. Papillary muscles were allowed to stabilize for 1 hour after mounting and then stretched until maximal developed tension occurred.⁸

Experimental Protocols
In all groups, RT, DT, T⁽⁺⁾, and T^(-) were measured (1) under basal conditions; (2) after pretreatment with various drugs; and (3) after cumulative dose-response curves for isoproterenol at 10^-9 to 10^-4 mol/L (isoproterenol hydrochloride, Sigma) were obtained. Isolated papillary muscles were pretreated with (1) vehicle (control group) (n=8); (2) Ang II, 10^-7 mol/L (n=6); (3) Ang II and L-NA, 10^-6 mol/L (n=6); (4) L-Arg, 10^-6 mol/L (n=6); (5) L-Arg and L-NA (n=8); (6) 8-Br-cGMP, 10^-6 mol/L (n=6); (7) Ang II and icatibant, 10^-6 mol/L (n=6); or (8) Ang II and indomethacin, 10^-5 mol/L (n=5). Ang II, L-Arg, and L-NA were obtained from Sigma; icatibant was a generous gift from Hoechst Pharmaceutical (Frankfurt, Germany). At the end of each experiment, muscle length was measured with a caliper. The muscle was then blotted dry and weighed and the cross-sectional area calculated, assuming the muscle to be a cylinder with a specific gravity of 1.

Data are expressed as mean±SEM. Statistical analysis was performed by ANOVA and Newman-Keuls test as appropriate. A value of P<.05 was considered significant.

	Results

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Papillary muscle cross-sectional area was similar in all groups, ranging from 0.63±0.07 to 0.83±0.04 mm². Resting tension was the same in all groups, ranging from 1.7±0.2 to 1.9±0.38 g/mm². Basal contractility was the same (Table 1), and drug pretreatment did not alter DT, T⁽⁺⁾, or T^(-).

View this table: [in this window] [in a new window]   Table 1. Basal Contractile Values

Increments in T⁽⁺⁾ (Fig 1), DT (Table 2), and T^(-) (Table 3) due to cumulative doses of isoproterenol were lower in the Ang II–treated group, and these effects of Ang II were completely blocked by L-NA (Fig 1; Tables 2 and 3).

View larger version (22K): [in this window] [in a new window]   Figure 1. Effect of Ang II in the presence or absence of L-NA on T(+) induced by isoproterenol. *P<.05, Ang II vs control or Ang II+L-NA; ##P<.05, control vs Ang II+L-NA (Nit-Arg).

View this table: [in this window] [in a new window]   Table 2. Effect of Various Pretreatments on Isoproterenol-Induced Maximal DT in Isolated Rat Cardiac Papillary Muscle

View this table: [in this window] [in a new window]   Table 3. Effect of Various Pretreatments on Isoproterenol-Induced T(-) in Isolated Rat Cardiac Papillary Muscle

Treatment with L-Arg partially blocked the effects of isoproterenol on T⁽⁺⁾ (Fig 2), DT (Table 2), and T^(-) (Table 3), and these effects were suppressed by L-NA. 8-Br-cGMP also partially blocked the effect of isoproterenol on T⁽⁺⁾ (Fig 2), DT (Table 2), and T^(-) (Table 3). However, the effect of Ang II on the response to isoproterenol was not altered by either the kinin antagonist icatibant or the cyclooxygenase inhibitor indomethacin (Fig 3; Tables 2 and 3).

View larger version (23K): [in this window] [in a new window]   Figure 2. Effect of (1) L-Arg with or without L-NA and (2) 8-Br-cGMP on T(+) induced by isoproterenol. *P<.05, L-Arg, L-NA+L-Arg, or 8-Br-cGMP vs control; ##P<.05, L-Arg vs L-NA (Nit-Arg)+L-Arg.

View larger version (21K): [in this window] [in a new window]   Figure 3. Effect of icatibant (Hoe 140), a kinin antagonist, or indomethacin, a cyclooxygenase inhibitor, on the blocking effect of Ang II on T(+) induced by isoproterenol. *P<.05, Ang II+icatibant or Ang II+indomethacin vs control.

	Discussion

Top Abstract Introduction Methods Results Discussion References

 
Our results demonstrate that Ang II blunts the contractile response to isoproterenol in isolated rat cardiac papillary muscles. This suggests that in the heart there is a functional negative coupling between the renin-angiotensin system and the ß-adrenergic system. Previous studies using rat sarcolemmal membranes from heart and liver have shown that Ang II inhibits the adenyl cyclase system, both under basal conditions and when stimulated with isoproterenol or glucagon; this inhibition was reversed by pertussis toxin, suggesting that an inhibitory guanine nucleotide regulatory protein (Gi) is involved in this effect.²

The concentrations of Ang II used to blunt the contractile response of cardiac papillary muscle to isoproterenol are much higher than those found in plasma (0.01 to 0.1 nmol/L); however, lower doses also have an inhibitory effect (Gómez Llambí, unpublished data, 1991). The dose of Ang II we used was selected to obtain the maximum inhibitory effect. It could be argued that the effect we observed occurs only when pharmacological doses of Ang II are used; however, in papillary muscles from the heart of two-kidney, one clip Goldblatt hypertensive rats (3 weeks after clipping) exposed to endogenous Ang II alone, we likewise observed that the response to isoproterenol was partially inhibited.⁸ It could also be that concentrations of Ang II in cardiac tissue are much higher than those in plasma, or that in situations characterized by high plasma renin activity, such as heart failure, chronic exposure to high Ang II has an inhibitory effect similar to that of the acute nonphysiological doses used in this study.⁹

We also found that inhibition of NO synthase by an L-Arg analogue, L-NA, reversed the effects of Ang II on the contractile response to isoproterenol; the effect of Ang II was mimicked by L-Arg, the precursor of NO. L-Arg may induce generation of NO in myocardial cells.⁴ Thus, Ang II and L-Arg could modulate the cardiac contractile response to ß-adrenergic stimulation via NO generation. There is evidence that NO synthase may modulate contractile function in the normal rat myocardium by inhibiting contractility.⁶ Inhibition of the contractile response to ß-adrenergic stimulation has been observed in cultured rat cardiocytes pretreated with endotoxin (lipopolysaccharide) to provoke the expression of inducible NO synthase and increase NO generation. This inhibition was abolished by N-monomethyl-L-arginine, confirming that NO inhibits the contractile response to ß-adrenergic stimulation.^{6 7} Nevertheless, the effect of L-Arg analogues on contractile function is debatable. Klabunde et al¹⁰ reported that inhibition of NO synthase with N^G-methyl-L-arginine inhibits not only the cardiac contractile response but also cAMP and cGMP concentrations in rat hearts stimulated with isoproterenol. This effect was not observed under basal conditions. On the other hand, Balligand et al^{6 7} suggest that NO inhibits the inotropic response to isoproterenol in isolated adult myocytes.

The origin of NO in the heart could be the endothelial cells of the endocardium and/or blood vessels, the nerves, and the conduction system, since there is evidence that NO synthase is present in the rat endocardium and in the nerves surrounding the cardiomyocytes.¹¹ In our preparation, Ang II probably acted on the endocardium, increasing intracellular calcium and stimulating NO generation. There is evidence that in endothelial and neuroblastoma cells, angiotensin induces NO release and cGMP formation via multiple receptor subtypes.^{12 13 14}

Since cGMP is one of the second messengers of NO, we also studied the effect of the stable analogue 8-Br-cGMP. We found that this compound likewise mimics the effect of Ang II, suggesting that in cardiac contractility induced by isoproterenol, the inhibitory effect of NO is mediated by cGMP. Furthermore, there are various indications that cGMP depresses the myocardial response to ß-adrenergic stimulation (for review, see Reference 5). The second messenger for ß-adrenergic stimuli is cAMP, which activates a dependent form of protein kinase. The kinase phosphorylates a specific substrate, phospholamban, leading to increased myocardial contractility. On the basis of our study, we cannot say where cGMP interacts with the ß-adrenergic system to inhibit contractility; however, we have previously reported that in isolated renal cells, stimulation of cGMP formation decreased cAMP.¹⁵ It could be that cGMP decreases cAMP via cGMP-stimulated cAMP phosphodiesterase activity or, more likely, via activation of a cGMP-dependent protein kinase that inhibits the calcium channel.^{5 16 17}

Neither the kinin antagonist icatibant nor the cyclooxygenase inhibitor indomethacin blocked the effects of Ang II on isoproterenol-induced contraction. This appears to be different from the coronary vasculature, where Ang II has been shown to act via kinins in stimulating NO and cGMP.³ The effects of Ang II on the papillary muscle were not mediated by kinins or prostaglandins.

Recent observations indicate that Ang II augments cytokine-stimulated inducible NO synthase expression and NO production in rat cardiac myocytes.¹⁸ Furthermore, in heart failure there is an increase in plasma Ang II⁸ and cytokines^{19 20} and also cardiac endothelial NO synthase and inducible NO synthase.^{21 22 23} These observations coupled with our own, as well as the recent finding that NO inhibits the positive inotropic response to ß-adrenergic stimulation in humans with left ventricular dysfunction,²⁴ could imply that in patients with heart failure part of the cardiac dysfunction is due to stimulation of the synthesis and release of NO by Ang II. These observations could also explain some of the beneficial effects of blocking the renin-angiotensin system in heart failure.

In conclusion, our findings indicate that Ang II and L-Arg negatively modulate the inotropic response to isoproterenol in the rat papillary muscle. This inhibitory effect appears to be mediated through generation of NO and cGMP. Attenuation of the contractile effect of isoproterenol by Ang II may be of clinical relevance since it could help explain why cardiac function improves in heart failure after blockade of the renin-angiotensin system.

	Selected Abbreviations and Acronyms

 

Ang II = angiotensin II 8-Br-cGMP = 8-bromo-cGMP DT = maximal developed tension L-Arg = L-arginine L-NA = N-nitro-L-arginine NO = nitric oxide RT = rest tension T(-) = maximal velocity of relaxation T(+) = maximal rate of rise in developed tension

	Acknowledgments

 
This study was supported by National Institutes of Health grant HL-28982 and University of Buenos Aires grant MA086.

	References

Top Abstract Introduction Methods Results Discussion References

 
1. Paulus WJ. Endothelial control of vascular and myocardial function in heart failure. Cardiovasc Drugs Ther. 1994;8:437-446. [Medline] [Order article via Infotrieve]

2. Anand-Srivastava MB. Angiotensin II receptors negatively coupled to adenylate cyclase in rat myocardial sarcolemma: involvement of inhibitory guanine nucleotide regulatory protein. Biochem Pharmacol. 1989;38:489-496. [Medline] [Order article via Infotrieve]

3. Seyedi N, Xu X, Nasjletti A, Hintze TH. Coronary kinin generation mediates nitric oxide release after angiotensin receptor stimulation. Hypertension. 1995;26:164-170. [Abstract/Free Full Text]

4. Moncada S, Palmer RMJ, Higgs EA. Nitric oxide: physiology, pathophysiology, and pharmacology. Pharmacol Rev. 1991;43:109-142. [Medline] [Order article via Infotrieve]

5. Lohmann SM, Fischmeister R, Walter U. Signal transduction by cGMP in heart. Basic Res Cardiol. 1991;86:503-514. [Medline] [Order article via Infotrieve]

6. Balligand J-L, Ungureanu D, Kelly RA, Kobzik L, Pimental D, Michel T, Smith TW. Abnormal contractile function due to induction of nitric oxide synthesis in rat cardiac myocytes follows exposure to activated macrophage-conditioned medium. J Clin Invest. 1993;91:2314-2319.

7. Balligand J-L, Kelly RA, Marsden PA, Smith TW, Michel T. Control of cardiac muscle cell function by an endogenous nitric oxide signaling system. Proc Natl Acad Sci U S A. 1993;90:347-351. [Abstract/Free Full Text]

8. Gende OA, Mattiazzi A, Camilion MC, Pedroni P, Taquini C, Gomez Llambi H, Cingolani HE. Renal hypertension impairs inotropic isoproterenol effect without beta-receptor changes. Am J Physiol. 1985;249:H814-H819.

9. Grinstead WC, Young JB. The myocardial renin-angiotensin system: existence, importance, and clinical implications. Am Heart J. 1992;123:1039-1045. [Medline] [Order article via Infotrieve]

10. Klabunde RE, Kimber ND, Kuk JE, Helgren MC, Förstermann U. N^G-methyl-L-arginine decreases contractility, cGMP and cAMP in isoproterenol-stimulated rat hearts in vitro. Eur J Pharmacol. 1992;223:1-7. [Medline] [Order article via Infotrieve]

11. Klimaschewski L, Kummer W, Mayer B, Couraud JY, Preissler U, Philippin B, Heym C. Nitric oxide synthase in cardiac nerve fibers and neurons of rat and guinea pig heart. Circ Res. 1992;71:1533-1537. [Abstract/Free Full Text]

12. Porsti I, Bara AT, Busse R, Hecker M. Release of nitric oxide by angiotensin-(1-7) from porcine coronary endothelium: implications for a novel angiotensin receptor. Br J Pharmacol. 1994;111:652-654. [Medline] [Order article via Infotrieve]

13. Zarahn ED, Ye X, Ades AM, Reagan LP, Fluharty SJ. Angiotensin-induced cyclic GMP production is mediated by multiple receptor subtypes and nitric oxide in N1E-115 neuroblastoma cells. J Neurochem. 1992;58:1960-1963. [Medline] [Order article via Infotrieve]

14. Chaki S, Inagami T. New signaling mechanism of angiotensin II in neuroblastoma neuro-2A cells: activation of soluble guanylyl cyclase via nitric oxide synthesis. Mol Pharmacol. 1993;43:603-608. [Abstract]

15. Stoos BA, Carretero OA, Garvin JL. ANF and bradykinin synergistically inhibit transport in M-1 cortical collecting duct cell line. Am J Physiol. 1992;263:F1-F6. [Abstract/Free Full Text]

16. Mery PF, Lohmann SM, Walter U, Fischmeister R. Ca²⁺ current is regulated by cyclic GMP-dependent protein kinase in mammalian cardiac myocytes. Proc Natl Acad Sci U S A. 1991;88:1197-1201. [Abstract/Free Full Text]

17. Conti M, Jin SL, Monaco L, Repaske DR, Swinnen JV. Hormonal regulation of cyclic nucleotide phosphodiesterases. Endocr Rev. 1991;12:218-234. [Abstract/Free Full Text]

18. Ikeda U, Maeda Y, Kawahara Y, Yokoyama M, Shimada K. Angiotensin II augments cytokine-stimulated nitric oxide synthesis in rat cardiac myocytes. Circulation. 1995;92:2683-2689. [Abstract/Free Full Text]

19. Balligand J-L, Ungureanu-Longrois D, Simmons WW, Pimental D, Malinski TA, Kapturczak M, Taha Z, Lowenstein CJ, Davidoff AJ, Kelly RA, Smith TW, Michel T. Cytokine-inducible nitric oxide synthase (iNOS) expression in cardiac myocytes: characterization and regulation of iNOS expression and detection of iNOS activity in single cardiac myocytes in vitro. J Biol Chem. 1994;269:27580-27588. [Abstract/Free Full Text]

20. Schulz R, Nava E, Moncada S. Induction and potential biological relevance of a Ca²⁺-independent nitric oxide synthase in the myocardium. Br J Pharmacol. 1992;105:575-580. [Medline] [Order article via Infotrieve]

21. de Belder AJ, Radomski MW, Why HJF, Richardson PJ, Bucknall CA, Salas E, Martin JF, Moncada S. Nitric oxide synthase activities in human myocardium. Lancet. 1993;341:84-85. [Medline] [Order article via Infotrieve]

22. Lewis NP, Tsao PS, Rickenbacher PR, Haywood GA, Leyen HVD, Valantine HA, Hunt SA, Gillingham ME, Cooke JP, Fowler MB. Induction of inducible nitric oxide synthase (iNOS) mRNA in the human cardiac allograft is associated with impaired LV contractile function. Circulation. 1994;90(suppl I):I-193. Abstract.

23. Studer R, Kastner S, Just H, Drexler H. Myocardial gene expression of endothelial nitric oxide synthase in ischemic and dilated cardiomyopathy. Circulation. 1994;90(suppl I):I-547. Abstract.

24. Hare JM, Loh E, Creager MA, Colucci WS. Nitric oxide inhibits the positive inotropic response to ß-adrenergic stimulation in humans with left ventricular dysfunction. Circulation. 1995;92:2198-2203.[Abstract/Free Full Text]

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This Article Abstract Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Llambí, H. G. Articles by Taquini, C.M. Search for Related Content PubMed PubMed Citation Articles by Llambí, H. G. Articles by Taquini, C.M. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Hazardous Substances DB NITRIC OXIDE