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Voltage‐gated K+ (Kv) currents sensitive to stromatoxin‐1 in Guinea pig urinary bladder smooth muscle
Author(s) -
Hristov Kiril L.,
Chen Muyan,
Petkov Georgi V.
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.781.4
Subject(s) - patch clamp , repolarization , guinea pig , membrane potential , immunocytochemistry , voltage clamp , bk channel , biophysics , electrophysiology , current clamp , smooth muscle , biology , chemistry , ion channel , microbiology and biotechnology , endocrinology , biochemistry , neuroscience , receptor
Members of the voltage‐gated K+ (Kv) channel superfamily have been suggested to mediate the resting membrane potential and the repolarization phase of the urinary bladder smooth muscle (UBSM) action potential. Here, we tested the hypothesis that stromatoxin‐1 (ScTx1)‐sensitive Kv channels are expressed and control the membrane excitability in Guinea pig UBSM cells. Freshly isolated UBSM cells were studied using RT‐PCR, immunocytochemistry and the perforated mode of the whole cell patch‐clamp technique. In all patch‐clamp experiments 100 nM paxilline, a specific BK channel inhibitor, was present in the recording solutions to separated the KV currents from the BK currents. Whole‐cell current was elicited by voltage‐step depolarizations to potentials between ‐70 to +30 mV. Application of 100 nM ScTx1 inhibited about 60% of the remaining whole‐cell current (n=5; P<0.05) and the effect was more pronounced at positive voltages. We have further identified the molecular fingerprints of the ScTx1‐sensitive Kv currents. RT‐PCR experiments on isolated cells revealed mRNA expression for Kv2.1 and Kv9.3 family members (n=3). The immunocytochemical experiments on freshly isolated single UBSM cells confirmed the expression of the Kv2.1 channel protein (n=3). Our data revealed that ScTx1‐sensitive Kv2.1 channels are expressed and serve to control cell excitability in Guinea pig UBSM cells. Supported by DK070909 to GVP