Betaxolol, a beta 1-adrenoceptor antagonist, inhibits Ca(2+)-induced contraction in skinned renal artery of the dog.
The effects of betaxolol on Ca(2+)-induced contractions in saponin-treated skinned canine renal arteries were examined. Betaxolol decreased the pCa (-log[Ca2+] M) 5.8-induced contraction at the same concentrations at which the drug relaxed the high K(+)-induced contraction in intact smooth muscles. The pCa-tension relation was shifted to the right and downward by betaxolol. Betaxolol inhibited the increase in Ca(2+)-induced contraction by calmodulin, and this effect of betaxolol was observed even at the concentration that had no effect when given alone. These results suggest that betaxolol decreases the Ca2+ sensitivity of the contractile system in skinned canine renal arteries, presumably by inhibiting calmodulin-mediated contractions.
Kitada
Y
Y
Pharmaceutical Laboratory I, Mitsubishi Chemical Corporation, Yokohama, Japan.
D000818:Animals; D015784:Betaxolol / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D011188:Potassium / Q000494:pharmacology; D012077:Renal Artery / Q000187:drug effects*; D014661:Vasoconstriction / Q000187:drug effects*
D015784:Betaxolol; D011188:Potassium; D002118:Calcium