title: Influence of streptomycin on spontaneous activity of clusters of cultured cardiac cells from neonatal rats.
abstract: In clusters of trypsinized ventricle cells from neonatal rats which exhibit slow response action potentials, streptomycin in concentrations from 0.17-5.5 mM significantly inhibits the beating rate. Microelectrode experiments performed at a concentration of 5.5 mM revealed a reduction in the slope of diastolic depolarization from 149 to 53 mV/s whereas the maximum diastolic potential depolarized from -42.4 to -33.6 mV which entailed a decrease in overshoot and maximum rate of rise of the action potential. We conclude that the decrease of the slope of diastolic depolarization mainly determines the slowing of the beating rate and that streptomycin interferes with the pacemaker mechanism usually associated with the slow response.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D002478:Cells, Cultured; D006321:Heart / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D051381:Rats; D013307:Streptomycin / Q000494:pharmacology*
chemical_list: D013307:Streptomycin