Hypertension, Vol 5, 943-950, Copyright © 1983 by American Heart Association
SW Ely, CW Sun, RM Knabb, JM Gidday, R Rubio and RM Berne
It has been demonstrated that resting coronary vascular resistance is
elevated with chronic hypertension and concomitant cardiac hypertrophy. The
present study employed a model of 6-week, one-kidney, one wrapped Page
hypertension to determine if the ability of the heart to match an increase
in oxygen demand with an increase in oxygen supply (coronary blood flow) is
impaired, and to determine if these vasoregulatory abnormalities are
attributable to inadequate adenosine release. Studies were performed in a
pentobarbital anesthetized, open-chest canine preparation using a
pericardial infusate method to determine adenosine release. Results showed
that dobutamine (a beta-receptor agonist) induced increases in myocardial
oxygen consumption (MVO2) over a physiological range (8-30 ml O2 X min-1 X
100 g-1) that were accompanied by an increase in coronary blood flow (CBF)
with no change in oxygen extraction. The relationship between MVO2 and CBF
was not different between the normotensive (NTC) and hypertensive (RHT)
animals. Pericardial infusate adenosine (PI ADO) concentrations were not
different for the same MVO2 and CBF, and the relationships for MVO2 vs PI
ADO as well as PI ADO vs CBF were unaltered by hypertension. However, the
relationship between PI ADO and coronary vascular resistance (CVR) was
altered in the RHT group such that a given PI ADO concentration was
associated with a significantly higher CVR. These data suggest that, over
the range of MVO2 studied, there are no limitations in metabolic regulation
of the coronary circulation of RHT animals, and that the higher CVR
encountered in the RHT group is not the result of a reduced release of the
endogenous vasodilator, adenosine.
ARTICLES
Adenosine and metabolic regulation of coronary blood flow in dogs with renal hypertension
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