Regulation of the slow Ca++ channels of myocardial cells.
Contraction of the heart is regulated by a number of mechanisms, such as neurotransmitters, hormones, autacoids, pH, intracellular ATP, and Ca++ ions. These actions are mediated, at least in part, by actions on the sarcolemmal slow (L-type) Ca++ channels, exerted directly or indirectly. The major mechanisms for the regulation of the slow Ca++ channels of myocardial cells includes the following. cAMP/PK-A phosphorylation stimulates the slow Ca++ channel activity, whereas cGMP/PK-G phosphorylation inhibits. DAG/PK-C phosphorylation and tyrosine kinase phosphorylation are suggested to stimulate the slow Ca++ channel activity. Intracellular application of Gs alpha protein increases the slow Ca++ currents (ICa(L)). Lowering of intracellular ATP inhibits ICa(L). Acidosis and increase in [Ca]i inhibits ICa(L). A number of changes in the Ca++ channels also occur during development and aging. Thus, it appears that the slow Ca++ channel is a complex structure, including perhaps several associated regulatory proteins, which can be regulated by a number of extrinsic and intrinsic factors, and thereby control can be exercised over the force of contraction of the heart.
Sperelakis
N
N
University of Cincinnati, OH 45267-0576, USA.
Katsube
Y
Y
Yokoshiki
H
H
Sada
H
H
Sumii
K
K
D000818:Animals; D002118:Calcium / Q000502:physiology; D015220:Calcium Channels / Q000502:physiology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002642:Chick Embryo; D002645:Chickens; D006152:Cyclic GMP / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000502:physiology; D006321:Heart / Q000254:growth & development / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D008954:Models, Biological; D009200:Myocardial Contraction; D010743:Phospholipids / Q000502:physiology; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D013654:Taurine / Q000502:physiology
D015220:Calcium Channels; D010743:Phospholipids; D013654:Taurine; D011505:Protein-Tyrosine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019204:GTP-Binding Proteins; D006152:Cyclic GMP; D002118:Calcium