Single L-type calcium channels in smooth muscle cells from resistance arteries of spontaneously hypertensive rats.
The amplitude of the whole-cell L-type Ca2+ channel current recorded from vascular smooth muscle cells is reportedly greater in spontaneously hypertensive rats (SHR) than in Wistar-Kyoto rats (WKY). However, no study has examined properties of single Ca2+ channels in arterial cells from these strains. To further test the hypothesis that activation of L-type Ca2+ channels in arterial smooth muscle cells would be enhanced in SHR, we recorded single Ca2+ channel currents in resistance mesenteric artery cells from SHR and WKY (8 to 9 weeks of age) using a cell-attached patch clamp technique. With 50 mmol/L Ba2+ in the recording pipette, the depolarizing pulse from a holding potential of -40 mV evoked the single L-type Ca2+ channel current. Opening of the single channels was more frequent in cells from SHR than from WKY. Single-channel conductance (20 pS) and open time (1 ms at 0 mV) did not differ in the two strains. The results suggest that an increased amplitude of the whole-cell current can be attributed to the enhanced opening of single Ca2+ channels in the arterial smooth muscle cells from SHR compared with WKY.
Ohya
Y
Y
Second Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan. ohya@intmed2.med.kyushu-u.ac.jp
Tsuchihashi
T
T
Kagiyama
S
S
Abe
I
I
Fujishima
M
M
D000818:Animals; D001158:Arteries / Q000378:metabolism / Q000503:physiopathology; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000502:physiology*; D006973:Hypertension / Q000378:metabolism / Q000503:physiopathology*; D015640:Ion Channel Gating; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000503:physiopathology*; D018408:Patch-Clamp Techniques; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D014655:Vascular Resistance
D015220:Calcium Channels; D002118:Calcium