Tachykinin NK1 and NK2 receptors mediate inhibitory vs excitatory motor responses in human isolated corpus cavernosum and spongiosum
Uretra, stenosi uretrale
Enzo Palminteri et Al.
Br J Pharmacol
Center for Urethral and Genitalia Reconstructive Surgery, Arezzo, Italy
Motor effects produced by tachykinins were studied in human isolated corpus spongiosum and cavernosum. In quiescent preparations neurokinin A caused potent contractions (pD(2)=8.3 – 7.9 respectively) prevented by the NK(2) receptor-selective antagonist nepadutant, whereas [Sar(9)]SP sulfone and senktide (NK(1) and NK(3) receptor-selective agonists) produced no effect or spare contractions. In KCl-precontracted corpus spongiosum septide (pD(2)=7.1) and [Sar(9)]SP sulfone (pD(2)=7.7) produced tetrodotoxin-resistant relaxations, abolished by the tachykinin NK(1) receptor-selective antagonist SR 140333. [Sar(9)]SP sulfone (1 microM) produced similar relaxations in precontracted corpus cavernosum.
Electrical field stimulation (EFS) elicited tetrodotoxin-sensitive relaxations, which were additive to those produced by [Sar(9)]SP sulfone. N(omega)-nitro-L-arginine (L-NOARG) totally prevented both [Sar(9)]SP sulfone- and EFS-induced relaxations. These results show that tachykinin NK(1) and NK(2) receptors mediate opposite motor effects in human penile tissues, suggesting a possible modulatory role of tachykinins on smooth muscle tone in these organs.
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