Nitric oxide relaxes rabbit corpus cavernosum smooth muscle via a potassium-conductive pathway.
We tested the hypothesis that acetylcholine-induced relaxation in cavernosal tissue is the result of nitric oxide production that alters K+ conductance. In the organ bath, acetylcholine- and sodium nitroprusside-induced relaxation of corpus cavernosum were significantly attenuated by tetraethylammonium. Basal [K+]i in cavernosal smooth muscle cells was 102 +/- 11 mM using a K+-sensitive fluorescent dye. Acetylcholine produced a decrease in [K+]i to 74 +/- 10 (n > 4, P < 0.05). Tetraethylammonium pretreatment blunted the acetylcholine- and sodium nitroprusside-induced decrease in [K+]i by 82%, (n > 5, P < 0.001), respectively. L-NMMA blunted the acetylcholine- and sodium nitroprusside-induced fall in [K+]i by 93% and 83% (n > 4, P < 0.001), respectively. These data suggest that acetylcholine-mediated cavernosal smooth muscle cells relaxation occurs through nitric oxide release with activation of K+ conductance.
Seftel
A D
AD
Department of Surgery, Division of Urology, Cleveland VA Medical Center, Case Western Reserve University, Ohio 44106, USA.
Viola
K A
KA
Kasner
S E
SE
Ganz
M B
MB
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009126:Muscle Relaxation / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009599:Nitroprusside / Q000494:pharmacology*; D010413:Penis / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D011817:Rabbits; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013997:Time Factors; D014665:Vasodilator Agents / Q000494:pharmacology*; D019323:omega-N-Methylarginine
D004791:Enzyme Inhibitors; D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D014665:Vasodilator Agents; D009599:Nitroprusside; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D019789:Tetraethylammonium; D001120:Arginine; D000242:Cyclic AMP; D019001:Nitric Oxide Synthase; D000109:Acetylcholine; D011188:Potassium