T3 C

Ca2 , as intracellular transmitter, mediates electromechanical coupling. It stimulates the release of neurotransmitters synaptic transmitters and hormones, the secretory activity of exocrine glands and of a number of enzymes e.g., glycogenolysis, phospholipase A, adeny-lylcyclase, phosphodiesterases . Ca2 activates some K channels, for example, in the heart, where Ca2 -sensitive K channels take part in the process of repolarization. Extracellular Ca2 stabilizes Na channels, reduces the...