Will the calcium channel agonist BAY K8644 inhibit halothane-induced impairment of calcium current?
The inhaled anesthetics impair transsarcolemmal calcium entry (ICa) in myocardial cells, although the mechanism of this interaction is not known. This inhibition of calcium entry has been implicated in the myocardial depression of the volatile anesthetics. To further characterize this interaction and to evaluate whether a calcium channel agonist could attenuate or prevent the inhibition of calcium entry, the effect of the calcium channel agonist BAY K8644 on the impairment of ICa by halothane was evaluated in single guinea pig ventricular myocytes. Calcium currents were evoked by means of the whole-cell voltage-clamp technique. Baseline peak ICa was higher in the cells exposed to 5 microM BAY K8644 (311 vs 206 pA/cm2, P less than 0.04). On exposure to 1% halothane, peak ICa was impaired to an identical degree whether or not cells were exposed to BAY K8644 (78% and 79% of baseline value). This is consistent with the suggestion that the effects of these agents on ICa are nonspecific. However, the increase in ICa suggests that appropriate calcium channel agonists might serve to ameliorate the myocardial depressant effects of halothane.
Baum
V C
VC
Department of Anesthesiology, University of California, Los Angeles.
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D004347:Drug Interactions; D006168:Guinea Pigs; D006221:Halothane / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D012508:Sarcolemma / Q000187:drug effects / Q000378:metabolism / Q000502:physiology
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D002118:Calcium; D006221:Halothane