An estimate of the participation of the sarcoplasmic reticulum in the intracellular Ca2+ regulation in adult and newborn ferret hearts.
The aim of the present study was to estimate the participation of the sarcoplasmic reticulum in the Ca2+ regulation of the contraction of newborn ferret heart. Cyclopiazonic acid has been used to block the sarcoplasmic reticulum Ca2+ pump in adult and newborn (1 month and 5-6 day old) ferret ventricles of intact and saponin-treated preparations. Cyclopiazonic acid induced a decrease of the amplitude of the caffeine contractures generated in saponin skinned fibers. The sensitivity of the sarcoplasmic reticulum Ca2+ uptake to cyclopiazonic acid was similar in adult and newborn hearts. In intact preparations, cyclopiazonic acid (1-20 microM) induced a negative inotropic effect on the twitch with a prolongation in its kinetics. The maximal decrease in the amplitude of the twitch was larger in adult (92.4%) than in 1 month old (86.5%) and 5-6 day newborns (72.5%). Contrary to other species, where the sarcoplasmic reticulum Ca2+ pump is not functional in neonatal heart, it is proposed that ferret myocardium shows an early maturation of sarcoplasmic reticulum function.
Bonnet
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Laboratoire de Physiologie Générale, URA CNRS 1340, Faculté des Sciences et des Techniques, Nantes, France.
Léoty
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C
D000818:Animals; D000831:Animals, Newborn; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005069:Evaluation Studies as Topic; D005289:Ferrets / Q000502:physiology*; D006352:Heart Ventricles / Q000187:drug effects / Q000254:growth & development*; D006652:Histological Techniques; D007211:Indoles / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D012503:Saponins; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000502:physiology*
D004791:Enzyme Inhibitors; D007211:Indoles; D012503:Saponins; D002110:Caffeine; D000252:Calcium-Transporting ATPases; D002118:Calcium; C000543:cyclopiazonic acid