Effect of Ketamine incubation on vascular reactivity in rats

REYES-TOSO, C.F., ARÁN, M., RICCI C., ALBORNOZ L., LOMBARDO, F., LINARES, L.M

Tandil, Argentina.

Congreso; ARGENTINIAN ASSOCIATION OF EXPERIMENTAL PHARMACOLOGY. XXXIV ANNUAL MEETING; 2002

ARGENTINIAN ASSOCIATION OF EXPERIMENTAL PHARMACOLOGY

When ketamine (Ket) is administered in bolus i.v injection it may be observed an hypertensive response. Furthermore hypotension may occur if sympathetic stimulation is prevented by other drugs. This last response seems to be due to an inhibitory action on vascular smooth muscle and endothelium-dependent relaxation. Rats were killed by decapitation and the thoracic aorta was removed. Rings were mounted on stainless steel hooks and suspended in tissue baths. Tension development was measured by isometric force transducers. Two rings were used as controls and two were incubated in the presence of Ket (10-4 and 10-5 M), and then cumulative dose-response curves to phenylephrine (Phe) and acetylcholine (Ach) were performed. Ket 10-4 M significantly attenuated the contraction elicited by KCl (83% vs controls, p < 0.001). and Phe (Ket : 46,8 ± 5,1% vs Control: 75,3 ± 2,9% respectively, p < 0.01). When Ket was added to the incubation chamber at 10-5 M, Phe (10-5 M) contraction was also reduced (Ket: 65.72 ± 2.78% vs Controls: 75.3 ± 2.9% p < 0.05). On Ach-induced relaxation it was observed a dual effect: Ket 10-4 M inhibited (Controls: 60.5± 2.96% vs Ket 11,22±2.21%, p < 0.001) and Ket 10-5 M increased the relaxation (Controls: 78.27 ± 2.99% vs Ket : 88,02 ± 1.16%, p < 0.05). These results are compatible with the view that in addition to the cardiovascular activation of ket, due to the central stimulation of the sympathetic nervous system, this drug exerts direct actions on arterial vessels