Vascular reactivities of simian ophthalmic and ciliary arteries

Abstract

Vascular reactivities to vasoactive substances were compared with ophthalmic and ciliary arteries (OAs and CAs) of Japanese monkeys. These two kind of arteries were perfused with Tyrode solution under a constant flow rate at 37 degrees C, respectively. Each drug solution was given by a microinjector into the endothelial side of the artery through a cannulated tubing, and responses were obtained as changes in perfusion pressure. Results were as follows: 1) Norepinephrine induced vasoconstriction in a dose-related manner in both arteries. The threshold dose was approximately 0.01 microgram in OAs and 0.1 microgram in CAs. The maximum value was approximately 45 mmHg in OAs and 20 mmHg in CAs. 2) Phenylephrine induced vasoconstriction in almost the same grade in both arteries. 3) Xylazine caused no significant change in perfusion pressure in both arteries. 4) Tyramine showed only small vasoconstrictor responses in both arteries. 5) 5-HT induced vasoconstriction in a dose-related manner in both arteries. The threshold dose was 0.001 microgram in CAs and 0.003 microgram in OAs, which indicated the smallest threshold dose in examined substances. However, the maximum increase in perfusion pressure was about 30 mmHg in OAs and 20 mmHg in CAs even at large doses. 6) PGF2 alpha induced a moderate increase in perfusion pressure, and the response in CAs was significantly greater than that in OAs. 7) KCl induced dose-dependent vasoconstriction. In CAs, the constriction induced by KCl was slightly greater than that in OAs but not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacological effects of latanoprost, prostaglandin E2, and F2 α on isolated rabbit ciliary artery

“…Although latanoprost is a PGF 2α -related compound, it is unlikely that the action is due to PGF 2α , because PGF 2α itself did not evoke relaxation of the muscle tested but only contracted it at 10 µM, the higher concentration used. In vitro, high concentrations of PGF 2α have been reported to cause constriction of monkey ophthalmic arteries and rabbit posterior ciliary arteries, as well as calf retinal arteries, an effect that may be mediated by TP receptor [10,16,17]. PGF 2α is known to spill over onto the TP receptor [4].…”

Effect of Cyclooxygenase Inhibition on Retinal and Choroidal Blood Flow during Hypercarbia in Newborn Piglets

“…In addition, the half-life of ketamine is 2-3 h, and at least 2 h were allowed to elapse between the ketamine administration and the first measurements in the study. Neither xylazine nor chloral hydrate have been shown to affect IOP (39)(40)(41).…”

Serotonin (5-HT) and the rat's eye

“…The reaction of the retinal vessels to 5-HT was first described in 1959 by Morlunghi & Volpi [17], followed by Tammisto [18], who described the transient blanching of the fundus after intravenous injection of 5-HT. A more detailed study by Okhubo & Chiba [19,20] showed the constrictive action on perfused canine ophthalmic arteries and human ciliary arteries. Williams et al [21] and Faraci et al [22], however, found no alteration in retinal bloodflow after 5-HT in healthy monkeys, whereas in atherosclerotic monkeys there was a marked reduction in bloodflow and a decrease in the reaction to light stimuli on the ERG.…”