Actin cytoskeletons regulate the stretch-induced increase of Ca2+ current in human gastric myocytes.
Using the whole-cell and single channel recording techniques, the influence of actin cytoskeletons on L-type Ca2+ current was investigated in human gastric smooth muscle cells. In isotonic condition, an actin depolymerizer cytochalasin D (Cyt-D) markedly decreased the whole-cell current (I(Ba)) without changing steady-state voltage dependency and single channel conductance. Intracellular dialysis of phalloidin, an actin polymerizer, significantly increased the I(Ba). Hypotonic stretch (222 mOsm/L) of the myocytes increased the I(Ba), and Cyt-D significantly inhibited the I(Ba) increase by the stretch. Phalloidin was without effect on the I(Ba) increase by the stretch. Phalloidin antagonized the Cyt-D inhibition of the stretch-induced I(Ba) increase. Neither heterotrimeric G protein modifiers (GTPgammaS and GDPbetaS) nor rho GTPase inhibitor (C3 exoenzyme) influenced the stretch-induced responses. These results reveal that the integrity of the actin cytoskeleton is an important factor which determines the activity of L-type Ca2+ channels and a response to stretch.
Kim
Jun Hee
JH
Department of Physiology, Sungkyunkwan University School of Medicine, Suwon 440-746, Republic of Korea.
Rhee
Poong-Lyul
PL
Kang
Tong Mook
TM
D000199:Actins / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000502:physiology*; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000502:physiology*; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology*; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D032389:Myocytes, Smooth Muscle / Q000502:physiology*; D013270:Stomach / Q000166:cytology / Q000502:physiology*; D013314:Stress, Mechanical
D000199:Actins; D020746:Calcium Channels, L-Type; D002118:Calcium