Abstract
K+ currents are known to regulate the excitability of corpus cavernosum myocytes and therefore to play a role in the control of penile erection and detumescence. We used electrophysiology and molecular cloning techniques to identify ion channel proteins that contribute to K+ currents in rabbit cavernosal myocytes. Currents were recorded from freshly isolated myocytes using whole-cell patch clamp techniques. Cavernosal myocytes expressed a delayed rectifier voltage-gated K+ current that appeared to contribute to the resting membrane potential. This voltage-gated K+ (Kv) current was inhibited by the nonselective compounds 4-aminopyridine (1-10 mM), (+)-fenfluramine (10 μM-1 mM), and Grammostola spatulata venom (1:100) in a dose-dependent and reversible fashion. Hanatoxin-1 (1 μM), a selective Kv2 channel inhibitor, partially inhibited the current, but α-dendrotoxin (200 nM), a Kv1 channel blocker, had no effect. The nucleotide sequence of K+ channel subunits was determined by polymerase chain reaction-based cloning techniques using RNA derived from cavernosal muscle strips and single identified myocytes. Molecular cloning, techniques identified the full-length sequence of the rabbit ortholog of the Kv2.2 α subunit. This sequence contains 911 amino acid residues and is 92% identical to the recently revised human Kv2.2 sequence. Identified cavernosal myocytes of the type used in physiological recordings expressed Kv2.2 messenger RNA. We conclude that Kv2.2 α subunits contribute to whole-cell currents in rabbit cavernosal myocytes. Further, Kv currents play a role in regulating membrane potential and hence excitability in rabbit cavernosal myocytes.
Original language | English (US) |
---|---|
Pages (from-to) | 899-910 |
Number of pages | 12 |
Journal | Journal of Andrology |
Volume | 23 |
Issue number | 6 |
State | Published - Nov 2002 |
Keywords
- Molecular cloning
- Patch clamp techniques
- Penile erection
- Potassium channels
- Smooth muscle
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Reproductive Medicine
- Endocrinology
- Urology