Effects of platelet-activating factor on nitrergic transmission in rabbit corpus cavernosum.
OBJECTIVE
The information currently available suggests that nonadrenergic noncholinergic (NANC) transmitters, particularly nitric oxide, are involved in the relaxation of penile erectile tissues. Platelet-activating factor (PAF) is a chemical mediator and is involved in many physiological and pathophysiological events. It is well known that several of the vascular actions of PAF are mediated by the generation of nitric oxide. We designed this study to test the hypothesis that PAF has an effect on NANC responses in rabbit corpus cavernosum strips.


METHODS
Rabbit corpus cavernosum strips were precontracted with phenylephrine (10(-5) mol/L). Isometric tension changes produced by carbachol (10(-9)-10(-5) mol/L), sodium nitroprusside (10(-8)-10(-5) mol/L) and electrical field stimulation (for 10 s at sequential frequencies of 2, 4, 8, 16, and 32 Hz as square-wave pulses of 50 mV) were recorded with a pressure transducer. These relaxations were compared to those obtained in the presence of PAF.


RESULTS
PAF had no effect on endothelium-dependent, endothelium-independent or electrical field stimulation-induced NANC relaxation responses in isolated rabbit corpus cavernosum strips. There was no statistically significant difference between the pD(2) and E(max) values for carbachol or sodium nitroprusside in the presence of PAF.


CONCLUSIONS
Our results suggest that PAF does not modify the endothelium-dependent, endothelium-independent or electrical field stimulation-induced NANC relaxation responses in isolated rabbit corpus cavernosum strips.
Department of Pharmacology, Medical School, Gazi University, 06510 Ankara, Turkey.
Sevil
S
Ozger
Süreyya
S
Barun
Ismail Mert
IM
Vural
Zeynep Sevim
ZS
Ercan
Yusuf
Y
Sarioğlu
D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D009424:Nervous System Physiological Phenomena; D009569:Nitric Oxide / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology; D010413:Penis / Q000294:innervation*; D010656:Phenylephrine / Q000494:pharmacology; D010972:Platelet Activating Factor / Q000494:pharmacology*; D011817:Rabbits; D009435:Synaptic Transmission / Q000187:drug effects* / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
D018679:Cholinergic Agonists; D010972:Platelet Activating Factor; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D009599:Nitroprusside; D010656:Phenylephrine; D009569:Nitric Oxide; D002217:Carbachol