Objective To investigate the eÂects of castration and Endothelium-dependent relaxation elicited by carbachol increased in the castrated group but the relaxtestosterone on the constricting eÂect of phenylephrine and endothelium-dependent and -independent ation induced by sodium nitroprusside did not change and those elicited by adenosine were strongly relaxing eÂects of diÂerent agonists in the corpus cavernosum of male rabbits. depressed when compared with controls. There were no significant changes in the pD 2 values of agonistMaterials and methods Twenty rabbits were castrated and 10 received testosterone replacement for 1 month induced relaxation responses in all groups. The relaxation elicited by electrical-field stimulation at lower after castration; 10 further rabbits underwent a sham operation and acted as controls. One month after frequencies increased in strips from castrated rabbits but at higher frequencies were unchanged when comoperation the rabbits were killed and their penises excised. Strips of corpus cavernosum were used for pared with controls. Castration-induced changes in the relaxation response of cavernosal strips were sigisometric tension measurements in organ chambers; concentration-response relationships for phenylephnificantly restored by in vivo testosterone replacement but those induced by phenylephrine were not. rine, carbachol, adenosine and sodium nitroprusside were obtained by adding the reagent cumulatively to Conclusion The lack of testosterone has an eÂect on the reactivity of the corpus cavernosum, indicating that the bath. Results The phenylephrine-induced contractions were testosterone has an important role in erectile function by a pre-or post-synaptic action on the corpus markedly lower, with no change in the pD 2 values (i.e. the negative logarithm of the concentration for cavernosum.
Reduction of relaxation response in hypothyroid rabbits corpus cavernosum can depend on a decreased release of nitric oxide (NO) from nitrergic nerves and endothelium.
These findings indicate that morphine, meperidine, fentanyl and remifentanil produce concentration-dependent and endothelium-independent relaxations in human being radial artery rings. Meperidine and fentanyl are more potent relaxant agents than morphine and remifentanil in the human being radial artery in vitro.
Obstructive jaundice is associated with a predisposition to systemic hypotension and acute renal failure. Altered vascular reactivity may contribute to the development of hypotension. In this experimental study on dogs, alterations in vascular contractile responses to noradrenaline, serotonin and KCl were investigated. Contractile responses to noradrenaline, serotonin,,, KCL and relaxation responses to papaverin and acetylcholine were provoked in isolated femoral arteries of both control dogs and animals with obstructive jaundice. In this situation concentration-response curves of noradrenaline and serotonin were blunted when compared with controls. This blunting disappeared when endothelium was removed. In rings precontracted with phenylephrine, EDRF relaxation responses to acetylcholine were increased significantly as compared to controls: at lower concentrations maximal relaxation response occurred. Contractile responses to KCl and relaxation responses to papaverin did not differ between the groups, endothelium present or removed. These results indicate that obstructive jaundice induces a decrease in vascular contractile responses and an increased EDRF relaxation response. We suggest that an excess in the amount of released EDRF may be one of the causes inducing systemic hypotension in obstructive jaundice.
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