Role of K+ channels to resting membrane potential of rabbit middle cerebral arterial smooth muscle cells.
- Author:
Nari KIM
1
;
Jin HAN
;
Euiyong KIM
;
Yun Hee KIM
;
Jae Hong SIM
;
Soo Cheon KIM
Author Information
1. Department of Physiology, College of Medicine, Inje University, Pusan, Korea.
- Publication Type:Original Article
- Keywords:
Resting membrane potential;
KCa channel;
KV channel;
Rabbit middle cerebral arterial smooth muscle cells
- MeSH:
Egtazic Acid;
Membrane Potentials*;
Membranes;
Muscle, Smooth*;
Myocytes, Smooth Muscle*;
Tea
- From:The Korean Journal of Physiology and Pharmacology
1999;3(6):547-554
- CountryRepublic of Korea
- Language:English
-
Abstract:
The aim of the present study is to investigate the contribution of Ca2+-activated K+ (KCa) channels and delayed rectifier K+ (KV) channels to the resting membrane potential (RMP) in rabbit middle cerebral arterial smooth muscle cells. The RMP and membrane currents were recorded using the whole-cell patch configuration and single KCa channel was recorded using the outside-out patch configuration. Using the pipette solution containing 0.05 mM EGTA, the RMP was -25.76+/-5.08 mV (n=12) and showed spontaneous transient hyperpolarizations (STHPs). The membrane currents showed time- and voltage-dependent outward currents with spontaneous transient outward currents (STOCs). When we recorded the membrane potential using the pipette solution containing 10 mM EGTA, the RMP was depolarized and did not show STHPs. The membrane currents showed no STOCs but only showed slowly inactivating outward currents. External TEA (1 mM) reversibly inhibited the STHPs, depolarized the RMP, reduced the membrane currents, abolished STOCs, and decreased the open probability of single KCa channel. When KV currents were isolated, the application of 4-AP (5 mM) depolarized the RMP. The important aspect of our results is that KCa channel is responsible for the generation of the STHPs in the membrane potential and plays an important role in the regulation of the RMP and KV channel is also responsible for the regulation of the RMP in rabbit middle cerebral arterial smooth muscle cells.
