title: Effect of captopril on the time-dependent variation of kaolin-induced writhing reaction.
abstract: Effect of captopril, an angiotensin-converting enzyme (ACE) inhibitor, on the time-dependent variation of kaolin-induced writhing reactions was examined in mice kept under conditions of light from 07:00 to 19:00 and dark from 19:00 to 07:00. The number of writhes was counted for 60 minutes after a single intraperitoneal injection of kaolin at 01:00, 07:00, 13:00, and 19:00. The number of writhes showed a time-dependent variation, with a peak at 19:00 and a trough at 07:00 in the control group. Captopril significantly increased the number of writhes after dosing at 01:00 and 07:00 (during the active period). The ACE activity following captopril dosing was significantly lower in the 07:00 than the 19:00 trial. These results suggest that the pharmacological effect of captopril varies with the dosing time, and the enhancement of the kaolin-induced writhing reaction is greater following dosing of the agent at nighttime in mice.
authors.affiliation: Department of Clinical Pharmacology, Jichi Medical School, Tochigi, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Sakamoto
authors.forename: K
authors.initials: K
authors.lastname: Sugimoto
authors.forename: A
authors.initials: A
authors.lastname: Fujimura
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D002216:Captopril / Q000494:pharmacology*; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology*; D003624:Darkness; D007616:Kaolin; D008027:Light; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D010146:Pain / Q000139:chemically induced / Q000503:physiopathology*; D007703:Peptidyl-Dipeptidase A / Q000097:blood*
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D007616:Kaolin; D002216:Captopril; D007703:Peptidyl-Dipeptidase A