The regulation of L-type Ca2+ currents in cardiac myocytes of hibernating animals.

The action of isoproterenol and BAY K 8644 on voltage-dependent Ca2+ currents in isolated ground squirrel cardiac myocytes was studied in two (active and hibernating) states of the animal. In cardiac myocytes of active animals the effect of both drugs was shown to depend on the holding potential. At Vh of about -50 mV both isoproterenol and BAY K 8644 increased the Ca2+ current and their action was additive. At Vh of about -20 mV, both drugs...