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Carotid haemodynamics in pigs during infusions of 8‐O‐DPAT: reduction in arteriovenous shunting is mediated by 5‐HT 1 ‐like receptors
Author(s) -
Bom Anton H.,
Verdouw Pieter D.,
Saxena Pramod R.
Publication year - 1989
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1989.tb11792.x
Subject(s) - shunting , hemodynamics , receptor , medicine , anesthesia , endocrinology , chemistry , cardiology
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‐HT 1A 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‐HT 2 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‐HT 1 ‐like and 5‐HT 2 receptors. 5 It is concluded that the effects of 8‐OH‐DPAT on arteriovenous anastomotic blood flow are mediated by 5‐HT 1 ‐like receptors. These receptors, however, cannot yet be classified as belonging to 5‐HT 1A 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.