title: Distribution of 3H-nitrendipine in the isolated perfused rat heart as revealed by electron microscopic autoradiography.
abstract: Subcellular distribution of 3H-nitrendipine was investigated in the isolated perfused rat heart by means of electron microscopic autoradiography. Mechanical measurements of cardiac contractile activity (dP/dt) were performed on the hearts used for autoradiography. There was a non-random pattern of silver grain distribution over the myocardial cells. The grain density, i.e. percentage of total grains/percentage of cell area, was determined for each cell component. A grain density higher than one was noted on the cell membrane, T-tubules and capillaries, indicating a significant incorporation of 3H-nitrendipine into the structures. Concentrations of unlabeled nitrendipine containing radiolabeled nitrendipine caused increased grain density and a decreased contractile activity (dP/dt) by 6% to 30%. It is therefore possible that the pharmacological action of nitrendipine is associated with the localization of 3H-nitrendipine on or in the cell membrane, T-tubules and capillaries.
mesh_terms: D000818:Animals; D001345:Autoradiography; D002196:Capillaries / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D003331:Coronary Vessels / Q000378:metabolism; D004727:Endothelium / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D008854:Microscopy, Electron; D008870:Microtubules / Q000378:metabolism; D008929:Mitochondria, Heart / Q000378:metabolism; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism* / Q000648:ultrastructure; D009210:Myofibrils / Q000378:metabolism; D009543:Nifedipine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D009568:Nitrendipine; D010477:Perfusion; D051381:Rats
chemical_list: D009568:Nitrendipine; D009543:Nifedipine