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ENHANCED CONTRACTILE RESPONSES MEDIATED BY DIFFERENT 5‐HT RECEPTOR SUBTYPES IN BASILAR ARTERIES, SUPERIOR MESENTERIC ARTERIES AND THORACIC AORTAS FROM STROKE‐PRONE SPONTANEOUSLY HYPERTENSIVE RATS
Author(s) -
Nishimura Y.,
Suzuki A.
Publication year - 1995
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1995.tb02986.x
Subject(s) - ketanserin , medicine , endocrinology , mesenteric arteries , basilar artery , agonist , cerebral arteries , antagonist , receptor antagonist , 5 ht receptor , receptor , chemistry , serotonin , artery
Summary 1. The contractile effects of 5‐hydroxytryptamine (5‐HT) in isolated ring preparations of basilar arteries (BA), thoracic aortas (TA) and superior mesenteric arteries (SMA) from stroke‐prone spontaneously hypertensive rats (SHRSP) and Wistar‐Kyoto (WKY) rats were investigated pharmacologically. 2. The pD 2 values (expressed as a negative logarithm of of EC 50 ) for 5‐HT in BA of SHRSP were greater than those of WKY. Increased pD 2 values for 5‐HT were also found in SMA and TA of SHRSP when compared to WKY. 3. Ketanserin (a 5‐HT 2 antagonist) produced a biphasic displacement of the concentration‐response curves for 5‐HT in BA of WKY and SHRSP but elicited a parallel rightward shift of the 5‐HT curve in SMA and TA of the two groups. 4. 5‐CT (a 5‐HT 1 agonist)‐induced contractions and their pD 2 values in the presence of ketanserin were larger in BA of SHRSP than in those of WKY, while 5‐CT did not contract SMA or TA in either group. 5. No significant difference was found in the contractile response induced by α‐methyl‐5‐HT (a 5‐HT 2 agonist) in BA from SHRSP and WKY, while the pD 2 values for α‐methyl‐5‐HT were increased in SMA and TA from SHRSP when compared to WKY. 6. These results suggest that the hyperresponsiveness to 5‐HT found in SHRSP arteries may be mediated by different 5‐HT receptor subtypes, that is, by 5‐HT 1 in BA and by 5‐HT 2 in SMA and TA.