Effects of L-dopa on myocardial contractile force: a reappraisal.
The apparent decrease in myocardial force of contraction observed after L-dopa, 10 mg/kg i.v., is artifactual since the maximum rate of left venticular isovolumic pressure rise (dP/dt) remains elevated. The apparent decrease is due to shrinkage in heart size secondary to venous "pooling". The decrease in contractile force parallels a decrease in cardiac output. A peripheral decarboxylase inhibitor and L-dopa produce a decrease in both contractile force and dP/dt. Strain gauge arch recordings may produce false-positive data during marked venous pooling.
D000818:Animals; D065105:Aromatic Amino Acid Decarboxylase Inhibitors; D001794:Blood Pressure / Q000187:drug effects; D002230:Carbidopa / Q000494:pharmacology; D002302:Cardiac Output / Q000187:drug effects; D004295:Dihydroxyphenylalanine / Q000494:pharmacology*; D004285:Dogs; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D013997:Time Factors
D065105:Aromatic Amino Acid Decarboxylase Inhibitors; D004295:Dihydroxyphenylalanine; D002230:Carbidopa