Effects of cholecystokinin octapeptide on rat cardiac function and the receptor mechanism.
The aim of this study was to explore the effects of cholecystokinin octapeptide (CCK-8) on cardiac function and the receptor mechanism in anesthetized rats. The mean arterial pressure (MAP), heart rate (HR), the left ventricle systolic pressure (LVP) and the maximal/minimum rate of LVP (+/-LV dp/dt(max)) were measured. The results obtained are as follows. (1) Low dose of CCK-8 (0. 4 microgram/kg i.v.) caused tachycardia and slight increase in MAP, LVP and LV dp/dt(max) (P<0.01), while medium dose (4.0 microgram/kg i.v.) and high dose of CCK-8 (40 microgram/kg i.v.) elicited a bradycardia and marked increase in MAP, LVP and LV dp/dtmax (P<0.01). (2) Proglumide (1.0 mg/kg i.v.), a CCK-receptor (CCK-R) antagonist, significantly inhibited the pressor effects of CCK-8, whilst it reversed the bradycardic responses (P<0.01). (3) Using reverse transcription polymerase chain reaction (RT-PCR), CCK-A receptor (CCK-AR) and CCK-B receptor (CCK-BR) mRNA were expressed in myocardium of rats. The above results indicate that CCK-8 may enhance cardiac function in a dose-dependent manner and elicit a change in HR, which is likely induced by the activation of CCK-R on myocardium.
Zhao
Xiao-Yun
XY
Department of Pathophysiology, Hebei Medical University, Shijiazhuang 050017, China. lingyiling@163.net
Ling
Yi-Ling
YL
Meng
Ai-Hong
AH
Shan
Bao-En
BE
Zhang
Jun-Lan
JL
D000818:Animals; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects*; D008297:Male; D009206:Myocardium / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011949:Receptors, Cholecystokinin / Q000187:drug effects*; D012844:Sincalide / Q000008:administration & dosage / Q000494:pharmacology*; D016277:Ventricular Function, Left / Q000187:drug effects*; D017725:Ventricular Pressure / Q000187:drug effects*
D011949:Receptors, Cholecystokinin; D012844:Sincalide