Hemodynamic effects of a potassium ionophore, lonomycin A.
Lonomycin A, an ionophorous antibiotic, exhibits a high transport rate for monovalent cations, especially potassium. The cardiovascular actions of lonomycin A were studied in anesthetized dogs. Lonomycin A administered intravenously at 30 micrograms/kg increased coronary blood flow slightly with relatively small alterations in other hemodynamic parameters. After 100 micrograms/kg, a slight and transient fall followed by an increase in blood pressure was observed. Coronary blood flow, cardiac output, left ventricular pressure, max dP/dt, and isometric ventricular segmental tension increased. Arterial venous O2 difference and total peripheral vescular resistance decreased. Above 300 micrograms/kg, dramatic alterations were produced in almost all hemodynamic parameters, and total peripheral vascular resistance was increased. Lonomycin A-induced positive inotropic action was partly inhibited by pretreatment with pindolol, however gradual shortening of the ventricular wall length was still observed. A positive chronotropic action induced by lonomycin A was inhibited by pindolol pretreatment in vivo. On the other hand, lonomycin A elicited a negative chronotropic effects in the isolated guinea-pig right atrium, concomitantly increasing resting tension. These results suggest that lonomycin A alone produces peripheral vascular dilation and effects cardiac functions, which are in turn modified by lonomycin A-induced cathecholamine release from nerve terminals.
Kaneko
K
K
Research Laboratories, Taisho Pharmaceutical Co., Ltd., Ohmiya, Japan.
Tsuchida
K
K
Yamazaki
R
R
Otomo
S
S
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003331:Coronary Vessels; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D007275:Injections, Intravenous; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D009550:Nigericin / Q000031:analogs & derivatives / Q000494:pharmacology*; D010869:Pindolol / Q000494:pharmacology
D000900:Anti-Bacterial Agents; C012410:lonomycin; D010869:Pindolol; D009550:Nigericin