Abstract
Panicogenic effects in humans of the selective cholecystokinin (CCKB) receptor agonist, cholecystokinin tetrapeptide (CCK4), have been reported to correlate with increases in heart rate (HR) and mean arterial pressure (MAP). Previous investigators have demonstrated that the nonselective CCKAand CCKB receptor agonist, sulfated cholecystokinin octapeptide, also produces increases in HR and mean arterial pressure. The purpose of our study is to determine if the cardiovascular changes induced by CCK4 are mediated by the CCKA or CCKB receptor subtype using selective CCK antagonists for both receptor subtypes. The rank order of potency of the CCK receptor antagonists affecting CCK4-induced HR and mean arterial pressure changes in the guinea pig corresponded to the rank order of potency for blockade of the CCKB receptor binding in rat cortex, phosphatidyl inositol turnover in AR 4-2J rat pancreatoma cells and inhibition of pentagastrin-induced acid secretion in the rat. The changes induced by CCK4 on HR, but not mean arterial pressure, appear to be species dependent as reflected by a decrease in the HR in the guinea pig and an increase in the dog. Nonetheless, the results from the antagonist studies indicate that the cardiovascular responses to CCK4 in both the guinea pig and dog are mediated by the CCKB receptor subtype.
Footnotes
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Send reprint requests to: Dr. Anthony A. Fossa, Department of General Pharmacology, Pfizer Central Research, Groton, CT 06340.
- Abbreviations:
- CCK
- cholecystokinin
- CCK4
- cholecystokinin tetrapeptide
- CCK8
- cholecystokinin octapeptide
- CCK8S
- sulfated cholecystokinin octapeptide
- CCK8US
- unsulfated cholecystokinin octapeptide
- PI
- phosphatidylinositol
- HR
- heart rate
- MAP
- mean arterial pressure
- Received June 11, 1996.
- Accepted December 10, 1996.
- The American Society for Pharmacology and Experimental Therapeutics
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