Prejunctional alpha(2A)-autoreceptors in the canine saphenous vein

• Type: Article in International Scientific Journal
• Date: 1997

Authors

Paiva, MQ (Author) Other; Alberto Mota (Author) FMUP; moura, d (Author) FMUP; Guimaraes, S (Author) Other

Journal

Title: Naunyn-Schmiedeberg's Archives of Pharmacology

Vol. 356

Pages: 368-373

ISSN: 0028-1298

Publisher: Springer Nature

Indexing

ISI Web of Knowledge - 6 Citations

Scopus - 7 Citations

Other information

Authenticus ID: P-001-ATV

DOI: 10.1007/pl00005064

Abstract (EN): The aim of the study was to determine the subtype of prejunctional alpha(2)-autoreceptors in the canine saphenous vein. Segments of the vein were incubated with H-3-noradrenaline and subsequently perifused with modified Krebs-Henseleit solution. Five periods of electrical stimulation were applied (S-1-S-5; each for 2 min, 1 Hz). Concentration-response curves for the inhibitory effect of the alpha(2)-adrenoceptor agonists oxymetazoline and UK-14,304 and for the facilitatory effect of nine antagonists were determined. Correlations between the pEC(30%)s for the antagonists obtained in the present study and the pK(i)s for the same antagonists obtained in tissues expressing only alpha(2A)-(HT29 cells), alpha(2B)-(neonatal rat lung), alpha(2C)- (OK cells) or alpha(2D)-adrenoceptors (rat submaxillary gland) showed that the alpha(2)-autoreceptors in the canine saphenous vein resemble most closely the alpha(2A)-subtype. Furthermore, oxymetazoline was a highly potent agonist (pIC(50%) = 8.10) and prazosin was a weak antagonist (pEC(30%) = 6.46), confirming that the alpha(2)-adrenoceptors involved in the modulation of the response to electrical stimulation of the canine saphenous vein do not belong to either the alpha(2B)- or alpha(2C)-subtype. On the other hand, the EC30% ratios phentolamine/rauwolscine and idazoxan/rauwolscine were much closer to the ratios obtained at alpha(2)-autoreceptors of the rabbit- (alpha(2A)) than of the guinea-pig brain cortex (alpha(2D)). The results suggest that the sympathetic nerves of the canine saphenous vein are endowed with alpha(2A)-adrenoceptors.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 6