Calcium release by ryanodine receptors in smooth muscle.
Recent experiments have revealed an unanticipated complexity in Ca2+ release processes in smooth muscle. While Ca2+ release via stimulation of phospholipase C activity and the gating of inositol-1,4,5-trisphosphate (InsP3) receptor Ca2+ channels has been well characterized, the role of the homologous family of sarcoplasmic reticulum (SR) Ca2+ channels, ryanodine receptors (RyRs), in excitation-contraction coupling in smooth muscle is less clear. These Ca2+-gated SR Ca2+ channels produce unitary Ca2+ sparks, which in turn open Ca2+-activated membrane ion channels such as Ca2+-activated Cl- channels (ClCa) and Ca2+-activated K+ channels. In this manner local Ca2+ sparks trigger spontaneous transient inward and outward currents, thereby driving physiological electrical activity in smooth muscle. Here we summarize some of our recent findings on Ca2+-induced Ca2+ release (CICR) and stretch-induced Ca2+ release (SICR) in smooth muscle.
Kotlikoff
M L
ML
Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853-6401, USA.
Wang
Yong-Xiao
YX
Xin
Hong-Bo
HB
Ji
Guanju
G
D000818:Animals; D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000502:physiology; D006321:Heart / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D009130:Muscle, Smooth / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D019837:Ryanodine Receptor Calcium Release Channel / Q000502:physiology*; D001743:Urinary Bladder / Q000502:physiology
D015220:Calcium Channels; D019837:Ryanodine Receptor Calcium Release Channel; D002118:Calcium