Unaltered caffeine-induced relaxation in the aorta of stroke-prone spontaneously hypertensive rats (SHRSP).
Caffeine-induced relaxation was studied in aortic segments from Wistar Kyoto rats (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP). Although acetylcholine-induced endothelium-dependent relaxation was impaired in preparations from SHRSP, the relaxation induced by caffeine was identical in both groups. In addition, caffeine-induced relaxation was not affected by removal of the endothelium in either group. The relaxation induced by N6,2'-O-dibutyryladenosine 3':5'-cyclic monophosphate (db-cAMP), a membrane-permeable analog of adenosine 3':5'-cyclic monophosphate (cAMP), was identical in both groups. No significant difference was observed in the increase in cAMP content induced by caffeine in the aortic smooth muscle between the groups, although the basal content was significantly higher in preparations from SHRSP. These results suggest that the relaxation induced by caffeine in these preparations is brought about by its direct effect on smooth muscle and that the response of the smooth muscle to caffeine, including cAMP production, is not altered in preparations from SHRSP compared with those from WKY.
Sekiguchi
Fumiko
F
Department of Anatomy and Physiology, School of Pharmaceutical Sciences, Kinki University, Higashi-Osaka, Japan. fumiko@phar.kindai.ac.jp
Miyake
Yoshimasa
Y
Kashimoto
Takafumi
T
Sunano
Satoru
S
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure; D001835:Body Weight; D003994:Bucladesine / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D008751:Methylene Blue / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D019335:Nitroarginine / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology
D004791:Enzyme Inhibitors; D010726:Phosphodiesterase Inhibitors; D014665:Vasodilator Agents; D019335:Nitroarginine; D002110:Caffeine; D003994:Bucladesine; D000242:Cyclic AMP; D000109:Acetylcholine; D008751:Methylene Blue