Amiloride Relaxes Rat Corpus Cavernosum Relaxation In Vitro and Increases Intracavernous Pressure In Vivo

The basal release of endothelium-derived catecholamines regulates the contractions of Chelonoidis carbonaria aorta caused by electrical-field stimulation

The contractions of Chelonoidis carbonaria aortic rings induced by electrical field stimulation (EFS) are not inhibited by blockade of the voltage-gated sodium channels by tetrodotoxin but almost abolished by the α1/α2-adrenoceptor antagonist phentolamine. The objective of this study was to identify the mediator(s) responsible for the EFS-induced contractions of Chelonoidis carbonaria aortic rings. Each ring was suspended between two wire hooks and mounted in isolated 10 ml organ chambers filled with oxygenated and heated Krebs-Henseleit's solution. Dopamine, noradrenaline and adrenaline concentrations were analysed by liquid chromatography coupled to tandem mass spectrometry. The contractions caused by dopamine and EFS were done in absence and presence of the nitric oxide (NO) synthesis inhibitor L-NAME, the NO-sensitive guanylyl cyclase inhibitor ODQ, the D1-like receptor antagonist SCH-23390, the D2-like receptor antagonists risperidone, quetiapine, haloperidol, and the tyrosine hydroxylase inhibitors salsolinol and 3-iodo-L-tyrosine. Basal concentrations of dopamine, noradrenaline and adrenaline were detected in Krebs-Henseleit solution containing the aortic rings. The catecholamine concentrations were significantly reduced in endothelium-denuded aortic rings. L-NAME and ODQ significantly potentiated the dopamine-induced contractions. The D2-like receptor antagonists inhibited the EFS-induced contractions of the aortic rings treated with L-NAME, whereas SCH 23390 had no effect. Similar results were observed in the contractions induced by dopamine in L-NAME treated aortic rings. These results indicate that catecholamines released by endothelium regulate the EFS-induced contractions. This may constitute a suitable mechanism by which reptilia modulate specific organ blood flow distribution.

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Summary:Chelonoidis carbonaria aortic rings release endothelium-derived catecholamines that modulate vascular smooth muscle reactivity.

Erectile Functional Restoration With Genital Branch of Genitofemoral Nerve to Pelvic Nerve Transfer After Spinal Root Transection in Rats

OBJECTIVE

To investigate the feasibility of erectile function restoration by the genitofemoral nerve to pelvic nerve transfer in rats.

METHODS

Thirty-six male rats were included in this study. Rats in the nerve transfer group (n = 12) were subjected to pelvic nerve, sacral roots, and L6 roots transection and then bilateral genitofemoral nerve to pelvic nerve transfer, rats in the nerve resection group (n = 12) were subjected to pelvic nerve, sacral roots, and L6 roots transection without nerve transfer, and rats in the control group (n = 12) served as controls. After reinnervation, intracavernous pressure (ICP) assessment was performed. Fluoro-Gold was injected into the corpus cavernosum. Immediately before euthanasia, transferred nerves were stimulated to test penile intracavernous pressure. The L6, S1, and L1-2 spinal cord segments were used for retrogradely labeled neurons. Regenerative nerve morphologic examination assessment was performed.

RESULTS

Genitofemoral nerve stimulation induced an increase in ICP in the nerve transfer group. The mean ICP in this group was (33.8 ± 9.4 mm Hg), which is higher than the mean value in the nerve resection group (3.9 ± 1.0 mm Hg) but lower than that in the control group (69.8 ± 12.2 mm Hg; P < .05). The formation of new neural pathways was confirmed by the appearance of Fluoro-Gold labeled neurons in the L-1 and L-2 spinal cord segments in the nerve transfer group. Regenerative nerve morphologic examination showed good axonal regeneration after genitofemoral nerve transfer.

CONCLUSION

Nerve regeneration can be obtained by genitofemoral nerve to pelvic nerve transfer, and erectile function can be restored.