Reduced L-type calcium current in the embryonic chick heart with persistent truncus arteriosus.
Calcium currents were examined in an experimental model in the embryonic chick heart with a congenital malformation known as persistent truncus arteriosus. This is a severe defect characterized by failure of conotruncal and aorticopulmonary septation of the embryonic heart tube. As a result, no separation into the aortic and pulmonary arteries occurs, and there is a common outflow tract. The hearts with persistent truncus arteriosus had a 26% greater ventricular to whole embryo weight, which indicated that the ventricles were enlarged. Both the low-threshold T-type (ICa.T) and the 1,4-dihydropyridine-sensitive L-type (ICa.L) Ca2+ currents were present in the ventricular myocytes from hearts at day 11 of incubation. However, day 11 hearts with persistent truncus arteriosus showed a twofold reduction in the peak magnitude of ICa.L at a test potential of + 10 mV without a concomitant reduction in the number of L channels detected by 1,4-dihydropyridine antagonist [(+)[3H]PN200-110] and agonist (Bay K 8644) receptor binding. The results indicated that an L channel regulatory mechanism other than protein synthesis was affected. These changes are consistent with responses to conditions of excessive hemodynamic burden that have been characterized in adult hearts.
Creazzo
T L
TL
Department of Anatomy, Medical College of Georgia, Augusta 30912-2000.
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000818:Animals; D002118:Calcium / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000378:metabolism; D015220:Calcium Channels; D002642:Chick Embryo; D004594:Electrophysiology; D006321:Heart / Q000503:physiopathology*; D017275:Isradipine; D009206:Myocardium / Q000378:metabolism; D010069:Oxadiazoles; D011978:Receptors, Nicotinic / Q000378:metabolism; D014339:Truncus Arteriosus, Persistent / Q000196:embryology / Q000503:physiopathology*
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D010069:Oxadiazoles; D011978:Receptors, Nicotinic; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D002118:Calcium; D017275:Isradipine