HYPERTENSION AND ENHANCED BETA-ADRENOCEPTOR-MEDIATED FACILITATION OF NORADRENALINE RELEASE PRODUCED BY CHRONIC BLOCKADE OF ADENOSINE RECEPTORS

• Type: Article in International Scientific Journal
• Date: 1995

Authors

GUIMARAES, S (Author) Other; Albino Teixeira, A (Author) FMUP; PAIVA, MQ (Author) Other

Journal

Title: British Journal of Pharmacology

Vol. 114

Pages: 1595-1598

ISSN: 0007-1188

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 15 Citations

Scopus - 15 Citations

Other information

Authenticus ID: P-001-H20

Abstract (EN): 1 The study was undertaken to compare the beta-adrenoceptor-mediated facilitation of noradrenaline release in the tail artery of vehicle-treated rats and of rats rendered hypertensive by chronic administration of 1,3-dipropyl-8-sulphophenylxanthine (DPSPX). Artery rings were loaded with [H-3]-noradrenaline, and five periods of electrical stimulation (1 Hz for 2 min) were applied. To eliminate the influence of prejunctional alpha(2)-adrenoceptors, the tissues were pre-exposed to 1 mu M phenoxybenzamine. 2 Isoprenaline caused a concentration-dependent increase of tritium overflow elicited by electrical stimulation. It was more effective in arteries from DPSPX-treated than in those from vehicle-treated rats; isoprenaline (27.8 nM) increased by 30% tritium overflow in vessels from vehicle-treated rats whereas isoprenaline (7.0 nM) produced a 30% increase in vessels from DPSPX-treated animals. Furthermore, the maximal effect of isoprenaline was a 32.6% increase in control rats but a 48.6% increase in DPSPX-treated rats. 3 These results show that the sympathetic nerve endings of the rat tail artery are endowed with prejunctional beta-adrenoceptors which mediate facilitation of noradrenaline release elicited by electrical stimulation. They also suggest that adenosine receptors and beta-adrenoceptors interact at the prejunctional level and that impairment of this 'talk' may lead to the development of a hypertensive state.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 4