title: [The distribution and mechanism of coronary arteriole cell resting membrane potential in guinea pigs].
abstract: OBJECTIVE
  To investigate the distribution and mechanism of coronary arteriole (CA) cell resting membrane potential (RP) in guinea pigs.
  
  
  METHODS
  Cell RP was recorded by intracellular microelectrode in isolated guinea pig coronary arteriole (diameter < 100 microm).
  
  
  RESULTS
  (1) Experiments were carried out in 112 cells with a mean RP of (-65 +/- 4.2)mV, the distribution of coronary arteriole cell RP fitted by Gaussian function was bimodal, one peak was -43 mV termed high RP, the other was -74 mV termed low RP. 10 mmol/L K+ and 3 micromol/ L acetylcholine(ACh) induced hyperpolarization in high-RP cells with (-7.4 +/- 0.87) mV (n = 13) and (-15 +/- 1.24) mV (n = 16) respectively, and induced depolarization in low-RP cells with (9.6 +/- 1.2) mV (n = 23) and (8.7 +/- 0.69) mV (n = 15) respectively. (2) The inward rectifier K+ channel (K(ir)) blocker Ba2+ caused concentration-dependent depolarization in low-RP cells with an EC50 of 120 micromol/L 100 micromol/L Ba2+ or higher could shift low-RP cells to high-RP state, the response of these cells to high K+ and ACh became a hyperpolarization.
  
  
  CONCLUSIONS
  The distribution of coronary vascular cell RP is bimodal, high K+ and ACh induce different responses in low and high RP cells. The two RP states are exchangeable mainly due to all-or-none conductance changes of K(ir).
authors.affiliation: The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, School of Medicine, Shihezi University, Shihezi 832002, China.
authors.forename: Xin-Zhi
authors.initials: XZ
authors.lastname: Li
authors.forename: Zhi-Ping
authors.initials: ZP
authors.lastname: Zhang
authors.forename: Jun-Qiang
authors.initials: JQ
authors.lastname: Si
authors.forename: Zhong-Shuang
authors.initials: ZS
authors.lastname: Zhang
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Wen-Yan
authors.initials: WY
authors.lastname: Shi
authors.forename: Ke-Tao
authors.initials: KT
authors.lastname: Ma
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001160:Arterioles / Q000166:cytology*; D003331:Coronary Vessels / Q000166:cytology / Q000502:physiology*; D005260:Female; D006168:Guinea Pigs; D008297:Male; D008564:Membrane Potentials / Q000502:physiology*; D008839:Microelectrodes; D009206:Myocardium / Q000378:metabolism; D024661:Potassium Channels, Inwardly Rectifying / Q000502:physiology*
chemical_list: D024661:Potassium Channels, Inwardly Rectifying; D000109:Acetylcholine