title: Cardiac action of KB-944, a new calcium antagonist.
abstract: A comparative study was made between the cardiac action of diethyl 4-(benzothiazol-2-yl)benzylphosphonate (KB-944) and those of nifedipine, diltiazem and verapamil in anesthetized dogs and isolated right atria of guinea pigs. In anesthetized dogs, KB-944 caused a dose-dependent fall in mean blood pressure and dose-dependent increase in coronary sinus outflow. Coronary sinus outflow oxygen pressure was increased with increasing coronary sinus outflow; and consequently, the coronary arterio-venous oxygen difference was decreased. The cardiac output was slightly increased, while the myocardial oxygen consumption and myocardial work were reduced. In the isolated right atria of guinea pigs, KB-944 produced a decrease in spontaneous atria rate, and at the concentration of 10(-6) g/ml atrial standstill was seen in few preparations. The contractile force was decreased by KB-944. Especially, KB-944 exerted the weakest effect on contractile force among the tested drugs. These actions of KB-944 are very similar to those of nifedipine, diltiazem and verapamil.
mesh_terms: D000758:Anesthesia; D000818:Animals; D052160:Benzothiazoles; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D003326:Coronary Circulation / Q000187:drug effects; D004285:Dogs; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D013844:Thiazoles / Q000494:pharmacology*
chemical_list: D052160:Benzothiazoles; D002121:Calcium Channel Blockers; D013844:Thiazoles; C035950:fosfedil