Electrical stimulation of the mesencephalic ventral tegmental area evokes skeletal muscle vasodilatation in the cat and rat

The Journal of Physiological Sciences - Tập 61 - Trang 293-301 - 2011
Kanji Matsukawa1, Tomoko Nakamoto1, Nan Liang1
1Department of Physiology, Graduate School of Health Sciences, Hiroshima University, Hiroshima, Japan

Tóm tắt

To test the hypothesis that the mesencephalic ventral tegmental area (VTA) plays a role in autonomic control of the cardiovascular system, we examined the cardiovascular effects of electrical stimulation of the mesencephalic ventral areas in anesthetized, paralyzed cats and rats. Electrical stimulation of the VTA for 30 s (100-μA current intensity; 40–50-Hz pulse frequency; 0.5–1-ms pulse duration) increased femoral blood flow by 130–162% in anesthetized cats and rats, whereas the identical stimulation of the substantial nigra (SN) failed to increase femoral blood flow. Electrical stimulation of the VTA also increased the arterial blood pressure and heart rate in anesthetized rats, but did not alter them in anesthetized cats. Accordingly, femoral vascular conductance was increased by 102–134% in both cats and rats. Atropine methyl nitrate (0.1 mg/kg) injected intravenously in the cats markedly attenuated the increases in femoral blood flow and vascular conductance. VTA stimulation was able to produce substantial increases in femoral blood flow and vascular conductance following a decerebration procedure performed at the premammillary and precollicular level in the cats, although their responses tended to attenuate to 55–69% of the control before the decerebration. Thus, it is likely that electrical stimulation of the VTA, but not the SN, is capable of evoking skeletal muscle vasodilatation, particularly via a sympathetically mediated cholinergic mechanism in the cat, and that the ascending projection from the VTA to the forebrain may not be responsible for the muscle vasodilatation.

Tài liệu tham khảo

Tan E, Goodchild AK, Dampney RAL (1983) Intense vasoconstriction and bradycardia evoked by stimulation of neurones within the midbrain ventral tegmentum of the rabbit. Clin Exp Pharmacol Physiol 10:305–309