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(Hypertension. 2004;43:87.)
© 2004 American Heart Association, Inc.

Scientific Contributions

Hypersensitivity of the Adrenal Cortex to Trophic and Secretory Effects of Angiotensin II in Lyon Genetically-Hypertensive Rats

Frédérick Aguilar; Ming Lo; Bruno Claustrat; José Maria Saez; Jean Sassard; Jacques Yuan Li

From the Inserm U-369, IFR-62 Laennec (F.A., J.M.S., J.Y.L.), Département de Physiologie et de Pharmacologie Clinique (F.A., M.L., J.S.), Faculté de Pharmacie, and Service de Médecine nucléaire (B.C.), Hôpital Neuro-Cardiologique, Lyon, France.

Correspondence to Jacques Y. Li, Faculté de Mécine Laennec, 7 Rue G Paradin, 69372 Lyon cedex 08, France. E-mail liyuan{at}lyon.inserm.fr

In Lyon hypertensive (LH) rats, a model of low-renin genetic hypertension, we investigated adrenal sensitivity to angiotensin II in terms of angiotensin II receptor (AT₁ and AT₂ receptors) regulation, morphological changes, and aldosterone and corticosterone secretion. Twelve-week-old LH rats, compared with normotensive LN and LL rats, were either untreated or treated for 4 weeks with AT₁ receptor antagonist irbesartan (50 mg/kg/d), angiotensin-converting enzyme inhibitor perindopril (3 mg/kg/d), or perindopril (3 mg/kg/d) plus angiotensin II infusion (200 ng/kg/min). At 16 weeks, untreated LH rats had high systolic blood pressure (P<0.05), low aldosterone (P<0.05), and increased corticosterone (P<0.05) plasma levels. AT₁-receptor binding density in the zona glomerulosa was similar in the three strains. In LH rats, angiotensin II infusion increased the relative adrenal weight from 10.5±0.3 to 16.7±0.7 mg/100g (P<0.05), whereas this change was very modest in normotensive rats. Zona glomerulosa enlarged and plasma aldosterone increased after angiotensin II infusion in the 3 strains, but more markedly in LH versus normotensive rats (2.4- versus 1.3- and 1.6-fold, respectively; 20- versus 10-fold in normotensive rats, P<0.05). Surprisingly, after angiotensin II infusion, despite the absence of angiotensin II receptors in the three strains, the zona fasciculata-reticularis enlarged 1.5-fold and plasma corticosterone increased 1.7-fold only in LH rats (P<0.05), suggesting an indirect control of this compartment by angiotensin II. The hypertrophy and hypersecretory activity of both zona glomerulosa and zona fasciculata-reticularis in LH rats in response to angiotensin II point to the adrenal cortex as a pivotal tissue in the pathophysiology of hypertension in LH rats.

Key Words: rats • hypertension, genetic • receptors, angiotensin II • adrenal gland • hypertrophy • aldosterone • corticosterone