Role of unsaturated fatty acids in the enhancement of muscarinic current by hyposmotic membrane stretch in guinea pig smooth muscle cells.
To investigate the function of exogenous unsaturated fatty acids in hyposmotic membrane stretch enhancement of muscarinic current (ICCh) in antral circular smooth muscle cells of guinea pig, we recorded the membrane current with the conventional whole cell patch-clamp technique. I(CCh) elicited by 50 micromol/L carbachol (CCh) at the holding potential of 20 mV under isosmotic condition was taken as control. Hyposmotic membrane stretch increased I(CCh) to 226.0+/-21.0%. When the cells were pretreated with 5 micromol/L arachidonic acid (AA), linoleic acid (LA) or oleic acid (OA), I(CCh)was inhibited to 3.8+/-0.6%, 35.2+/-0.8% and 66.6+/-0.6% respectively. Hyposmotic membrane stretch increased I(CCh) to 106.0+/-2.5%, 173.2+/-6.8% and 222.1+/-11.0% of the control respectively. Five micromol/L AA inhibited hyposmotic membrane stretch-enhanced I(CCh) by 51.2+/-3.8%, while the control I(CCh) under isosmotic condition was inhibited by 96.2+/-1.6%. The results suggest that unsaturated fatty acids inhibited I(CCh) and the inhibitory effect is more significant when the unsaturation degree is increased. However, the unsaturated fatty acids are not involved in the increase of I(CCh) induced by hyposmotic membrane stretch.
Cui
Yi-Feng
YF
Department of Physiology, Yanbian University College of Medicine, Yanji 133000.
Li
Lin
L
Yu
Yong-Chun
YC
Jin
Zheng-Yuan
ZY
Li
Zai-Liu
ZL
Xu
Wen-Xie
WX
D000818:Animals; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D006168:Guinea Pigs; D008564:Membrane Potentials / Q000187:drug effects; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000502:physiology*; D009997:Osmotic Pressure; D018408:Patch-Clamp Techniques; D011706:Pyloric Antrum / Q000166:cytology* / Q000502:physiology; D011976:Receptors, Muscarinic / Q000502:physiology*; D012965:Sodium Chloride
D005231:Fatty Acids, Unsaturated; D011976:Receptors, Muscarinic; D012965:Sodium Chloride