کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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2536634 | 1559155 | 2007 | 8 صفحه PDF | دانلود رایگان |
Angiotensin and endothelin are vasoactive peptides with neuromodulatory effect, however their interactions in facilitating neurotransmission are largely unknown. In the present study, effort was made to examine how endothelin 1 modulates angiotensin II-potentiated purinergic neurotransmission in prostatic rat vas deferens. Both peptides facilitated field-stimulated muscle contraction in a concentration-dependent manner with Kd values of 16.97 ± 6.47 and 2.46 ± 0.83 nM for angiotensin II and endothelin 1, respectively. Hill plot analysis gave Hill constants of 0.91 ± 0.15 and 0.97 ± 0.26 for angiotensin II and endothelin 1, respectively. Correlation analysis indicated that the extent of potentiation by angiotensin II, but not endothelin 1, was proportional to the basal field-stimulated muscle contraction. In the presence of low concentrations of endothelin 1 (≤ 3 nM), angiotensin II-potentiated field-stimulated contraction was further enhanced by endothelin. However, in the presence of high concentrations of endothelin 1 (≥ 10 nM), a much increased basal field-stimulated contraction was observed, and the addition of angiotensin II did not elicit any further enhancement in the contractile response. Intriguingly, after prolonged exposure of prostatic rat vas deferens to a high concentration of endothelin 1, the addition of angiotensin II induced a refractory response to field-stimulation. Taken together, our result indicated that endothelin 1 augmented angiotensin II-facilitated purinergic neurotransmission in prostatic rat vas deferens at low concentrations, but inhibited gradually at high concentrations.
Journal: European Journal of Pharmacology - Volume 557, Issues 2–3, 28 February 2007, Pages 204–211