Effects of an indazole derivative, FKK, a novel bronchodilator, on the cardiovascular system in dogs

The cardiovascular effects of FKK (2,3-dihydro-7-methyl-9-phenyl-1H-pyrazolo [1,2-a]indazolium bromide) were compared with those of aminophylline and isoproterenol in anesthetized dogs. The doses of the three drugs used were sufficient to cause significant tracheal dilation in the anesthetized dogs. FKK (0.1-3.0 mg/kg, i.v.) slightly increased respiratory frequency, left ventricular (LV) dp/dt max and myocardial contractile force. A slight increase followed by a decrease was observed in systemic blood pressure and LV systolic pressure. The drug caused direct vasodilation in the coronary, mesenteric and femoral vasculatures, but had no effect on the renal vasculature. Similar results were obtained with aminophylline (0.3-30.0 mg/kg, i.v.) and isoproterenol (0.003-0.3 microgram/kg, i.v.), but their effects on the measured cardiac parameters were much more potent and long-lasting than those of FKK, when compared in doses producing a bronchodilation in similar magnitude. It is particularly pertinent that FKK (30 mg/kg, i.d., enough to cause marked bronchodilation), unlike aminophylline (30 mg/kg, i.d.), did not significantly influence the cardiovascular system.