title: Cyclic GMP regulates the Ca-channel current in guinea pig ventricular myocytes.
abstract: The effect of intracellular perfusion with cyclic GMP (cGMP) on Ca current (Ica) was investigated in Cs-loaded isolated cells from guinea pig ventricle using the whole-cell patch-clamp technique and a perfused patch pipette. cGMP (5 microM) strongly reduced Ica which had been elevated by intracellular perfusion with 50 microM of either cyclic AMP (cAMP) or its hydrolysis-resistant analog 8-Bromo-cAMP. In addition, cGMP prevented the stimulation of Ica by IBMX, a phosphodiesterase inhibitor. The membrane permeant cGMP analog 8-Bromo-cGMP (100 microM), when applied outside the cell, also antagonized the stimulatory effect of IBMX on Ica. It is concluded that cGMP inhibits Ica in guinea pig ventricular cells by a mechanism different from the activation of a cGMP-stimulated phosphodiesterase recently found in frog ventricular cells.
authors.affiliation: Dipartimento di Biologia Animale, Università di Torino, Italy.
authors.forename: R C
authors.initials: RC
authors.lastname: Levi
authors.forename: G
authors.initials: G
authors.lastname: Alloatti
authors.forename: R
authors.initials: R
authors.lastname: Fischmeister
mesh_terms: D000818:Animals; D015220:Calcium Channels / Q000378:metabolism*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism*; D004594:Electrophysiology; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000378:metabolism*; D010477:Perfusion; D013997:Time Factors
chemical_list: D015220:Calcium Channels; D000242:Cyclic AMP; D006152:Cyclic GMP