Analysis of the contraction induced by isoproterenol in isolated cerebral and femoral arteries of cat

Abstract

The vasoconstrictor responses induced by isoproterenol in cylindrical segments of posterior communicating and femoral arteries of the cat were analyzed.For this purpose, dose-response curves for isoproterenol before and after addition of propranolol (5 X 10(-09) to 10(-06) M) or phentolamine (10(-06) M) to the bath were determined.Propranolol did not significantly change the contraction induced by isoproterenol in cerebral and femoral arteries.Phentolamine reduced the contractile responses of cerebral arteries evoked by all concentrations of isoproterenol.However phentolamine shifted the dose-response curve to isoproterenol in femoral arteries to the right, the pA2 value for this antagonist being 6.74.These results indicate that the alfa adrenoceptors are involved in the contraction caused by isoproterenol in femoral arteries, whereas in brain arteries other receptors or mechanisms are also likely involved.