Effects of prostaglandin E1 on isolated dog renal artery

Actions of prostaglandin (PG) E1 were investigated using isolated dog renal arterial strips. Norepinephrine increased the tension of the renal arterial strips contracted with potassium, and this response was depressed by phentolamine. Isoproterenol produced relaxant effects on these arteries, and this response was converted to contractile one by propranolol. Diltiazem dose dependently relaxed the potassium-contracted strips. PGE1 (10(-9)-3 X 10(-8) Gm./ml.) constricted the renal arterial strips, while in higher concentrations (10(-7)-3 x 10(-7) Gm./ml.) it caused relaxations of them. Contractile responses by PGE1 were not affected by phentolamine or phenoxybenzamine, but were suppressed by diltiazem. On the other hand, relaxant effects of PGE1 were not changed by propranolol. Papaverine or theophylline significantly inhibited the contractions induced by PGE1. From these results it is suggested that (1) in the dog renal artery adrenergic alpha-receptors must be more dominant than beta-receptors; (2) PGE1 will produce a depolarization of renal arterial smooth muscle and/or increase an active transport of calcium ions into smooth muscle cells; and (3) the relaxant responses by PGE1 may be related to an increase in cellular cyclic adenosine monophosphate (AMP) contents.