Contrasting effects of betaxolol and propranolol on Ca(2+)-activated contractions in skinned fibers from canine coronary arteries and ventricular muscles

Cardiovascular Drugs and Therapy
Y Kitada

Abstract

The effects of some beta-adrenoceptor antagonists (atenolol, betaxolol, bunitrolol, labetalol, pindolol, and propranolol) on Ca2+ (pCa 5.8)-activated tension development in chemically skinned fibers from canine coronary artery and right ventricular trabeculae were studied. In skinned coronary arteries, Ca(2+)-activated tension development was decreased by betaxolol and propranolol at concentration of more than 10(-5) and 10(-4) M, respectively. The pCa-tension relationships were shifted to the right and down by betaxolol. In contrast, in skinned cardiac muscle Ca(2+)-activated tension development was increased by betaxolol and propranolol at the same range of concentrations as in coronary arteries, with no change in maximum tension. The pCa-tension relation was shifted to the left by betaxolol. Other beta-adrenoceptor antagonists (atenolol, bunitrolol, labetalol, and pindolol) had no effect on Ca(2+)-induced contraction in either muscle type. These results indicate that among beta-adrenoceptor antagonists, only betaxolol and propranolol can directly modulate the Ca2+ sensitivity of myofilaments and have opposite effects on the contractile system in canine cardiac and vascular smooth muscle.

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Citations

Jun 30, 2001·European Journal of Pharmacology·A BundkirchenR H Schwinger
Oct 12, 2010·Progress in Retinal and Eye Research·Makoto Araie, Chihiro Mayama
Mar 27, 2003·Journal of Cardiovascular Pharmacology·Hiroshi AsanumaMasafumi Kitakaze

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