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- Title
Hypertension and the absence of EDHF-mediated responses favour endothelium-dependent contractions in renal arteries of the rat.
- Authors
Michel, F. S.; Man, G. S.; Man, R. Y. K.; Vanhoutte, P. M.
- Abstract
<bold>Background and Purpose: </bold>Experiments were designed to determine the modulation by nitric oxide (NO) and endothelium-dependent hyperpolarizations (EDHF-mediated responses) of endothelium-dependent contractions in renal arteries of normotensive and hypertensive rats.<bold>Experimental Approach: </bold>Rings, with or without endothelium, of renal arteries of 8-month-old Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were suspended in myographs for isometric force recording.<bold>Key Results: </bold>ACh evoked relaxations in preparations contracted with phenylephrine. L-NAME (inhibitor of NOS) attenuated (WKY) or abolished (SHR) these relaxations. TRAM-34 plus UCL 1684 (inhibitors of EDHF-mediated responses) did not decrease the relaxation, except in rings of WKY when L-NAME was also present. High concentrations of ACh caused a secondary increase in tension, augmented in rings of WKY by L-NAME or TRAM-34 plus UCL 1684. The increase in tension was prevented by indomethacin. Under baseline tension, ACh induced endothelium-dependent contractions, prevented by indomethacin (COX inhibitor) or terutroban (TP receptor antagonist). The calculated endothelium-dependent contractions were larger in rings of SHR compared with those of WKY. In preparations of SHR, the contractions were augmented by L-NAME in the presence of SC19220 (EP-1 receptor antagonist). In arteries of WKY, the endothelium-dependent contractions were augmented by TRAM-34 plus UCL 1684. The responses were reduced by SC19220.<bold>Conclusions and Implications: </bold>In the renal artery of the rat, EDCF-mediated contractions are augmented by hypertension. The endothelium-dependent contractions are facilitated by NOS inhibition (in the presence of an EP-1 receptor antagonist) and by the withdrawal of EDHF-mediated responses.
- Subjects
HYPERTENSION; NITRIC oxide; ENDOTHELIUM; RENAL artery; INDOMETHACIN; LABORATORY rats; PHARMACOLOGY
- Publication
British Journal of Pharmacology, 2008, Vol 155, Issue 2, p217
- ISSN
0007-1188
- Publication type
journal article
- DOI
10.1038/bjp.2008.256