Cholecystokinin-8 (CCK-8) has no effect on heart rate in rats lacking CCK-A receptors.
Heart rate responses to i.v. administration of cholecystokinin-8 (CCK-8) were investigated in Otsuka Long-Evans Tokushima Fatty (OLETF) rats lacking CCK-A receptors and control Long-Evans Tokushima Otsuka (LETO) rats. The heart rate decreased after i.v. administration of 3 nmol.kg(-)(1) of CCK-8 in LETO rats, but not in OLETF rats. Bradycardia in the LETO rats disappeared after treatment with MK-329, but not after treatment with L-365,260. The expression of CCK-A receptor precursor mRNA was found exclusively in the atrium in LETO rats. These results suggest that CCK-8 decreases heart rate via CCK-A receptors located in the atrium of the rats.
Kurosawa
M
M
Basic Medical Research Center, International University Health and Welfare, Otawara, Tochigi 324-8501, Japan. mieko-ku@iuhw.ac.jp
Iijima
S
S
Funakoshi
A
A
Kawanami
T
T
Miyasaka
K
K
Bucinskaite
V
V
Lundeberg
T
T
D000818:Animals; D001570:Benzodiazepinones / Q000494:pharmacology; D015139:Blotting, Southern; D001919:Bradycardia; D018076:DNA, Complementary / Q000378:metabolism; D020109:Devazepide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006325:Heart Atria / Q000378:metabolism; D006339:Heart Rate / Q000187:drug effects*; D006727:Hormone Antagonists / Q000494:pharmacology; D008297:Male; D010671:Phenylurea Compounds / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020334:Rats, Inbred OLETF; D020318:Rats, Long-Evans; D043886:Receptor, Cholecystokinin A; D011949:Receptors, Cholecystokinin / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology*; D012844:Sincalide / Q000378:metabolism / Q000494:pharmacology*; D013997:Time Factors
D001570:Benzodiazepinones; D018076:DNA, Complementary; D006727:Hormone Antagonists; D010671:Phenylurea Compounds; D012333:RNA, Messenger; D043886:Receptor, Cholecystokinin A; D011949:Receptors, Cholecystokinin; C058121:L 365260; D020109:Devazepide; D012844:Sincalide