Analysis of the vasodilator action of alprenolol

Effects of Several Beta-Blocking Agents on the Development of Hypertension in Spontaneously Hypertensive Rats

“…However, of the ,3-blockers used in the present study, peripheral vasodilatation have been reported only with propranolol and in the dog (29,30), the compound which failed to produce a hypotensive effect in the pithed rat. Furthermore, the duration of the vasodilatatory effect observed with ~-blockers in the past was too short (29,30,31) to explain the long-term antihypertensive effects noted in the present study. Further studies are urgently needed to elucidate the peripheral mecha nisms of antihypertensive effects of a-blockers.…”

Correlation between vasodilator potencies of .BETA.-adrenoceptor blocking drugs and their chemical structures.

“…It is also unlikely that the vasodilation is concerned with their local anesthetic actions, because their relative potencies for the local anesthetic action differed markedly from those for the vasodilator action, as reported previously (3). As regards the mechanism underlying this distinct vasodilator action of 9-adrenoceptor blocking drugs, we have already proposed that /3-adrenoceptor blocking drugs probably inhibit calcium transport (3,7). The inhibition of calcium transport by pronethalol and propranolol in cardiac muscle has already been suggested by Fleckenstein et al (8).…”

“…Perfusion pressure was kept constant at approx. 120 mm Hg by shunting a fraction of blood through a Starling pneumatic re sistance to the external jugular vein (3). Sodium heparin was given at a dose of 500 units/ kg i.v.…”