Carotid haemodynamics in pigs during infusions of 8‐O‐DPAT: reduction in arteriovenous shunting is mediated by 5‐HT1‐like receptors

Open Access
Publisher Website
Google Scholar
Abstract
1 The effects of intracarotid infusions of 8-hydroxy-2-[di-n-propyl-amino]-tetralin (8-OH-DPAT) on heart rate, blood pressure and carotid blood flow and its distribution were studied in anaesthetized pigs by use of radioactive microspheres of 15 μm diameter. 2 Control experiments with physiological saline showed that systemic and carotid haemodynamics remain essentially unchanged during the experimental period. In contrast to results obtained in rat, cat and dog experiments, 8-OH-DPAT did not decrease arterial blood pressure. 3 8-OH-DPAT, which has a high affinity and is selective for the 5-HT1A recognition site, caused a dose-related decrease in arteriovenous anastomotic (non-nutrient) blood flow, resulting in a decrease in carotid blood flow. At the highest dose used, a small increase in arteriolar (nutrient) blood flow was observed. 4 The decrease in arteriovenous anastomotic and carotid blood flow induced by 8-OH-DPAT was not significantly modified by pretreatment with the 5-HT2 receptor antagonist ketanserin (0.5 mg kg−1), but was markedly reduced by pretreatment with methiothepin (1 mg kg−1), which blocks both the 5-HT1-like and 5-HT2 receptors. 5 It is concluded that the effects of 8-OH-DPAT on arteriovenous anastomotic blood flow are mediated by 5-HT1-like receptors. These receptors, however, cannot yet be classified as belonging to 5-HT1A receptor subtype. Since a number of antimigraine drugs reduce arteriovenous shunting, it is tempting to suggest that 8-OH-DPAT may have similar clinical efficacy.

This publication has 35 references indexed in Scilit: