Effects of microinjection of angiotensin II into the subnucleus commissuralis of nucleus tractus solitarii on the cardiovascular system of rabbits
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Microinjection of angiotensin (A II), 4 μg, into the subnucleus commissuralis of nucleus tractus solitarii (CNTS) was made in rabbits under urethane anesthesia in order to investigate its cardiovascular effects. Experimented animals were divided into five groups: 1. In control group 0.5 μ1 of normal saline was injected into CNTS. There was no significant change in mean arterial pressure (MAP) and heart rate (HR). 2. AII, 4 μg, dissolved in 0.5 μ1 saline was injected into the same region. MAP increased markedly, and HR decreased. 3. After severing bilateral sinus nerves and depressor nerves, 4μg of AII was injected. MAP increased more markedly, but HR showed slight reduction. 4. After microinjection of 4 μg A II into CNTS, the arterial baroreceptor reflex sensitivity (ABS) was determined by means of i. v. injection of adrenaline (5 μg/kg). ABS showed no significant change. 5. Previous injection of naloxone (3nmol) did not influence the pressor response to AII. The results suggest primary effect of the microinjection of AII into CNTS on vasomotor neurons without apparent effect on the cardiac neurons, and no effect of the endogenous opioid system in CNTS on the pressor response to A II during resting condition.
Key wordssubnucleus commissuralis of nucleus tractus solitarii angio tensin II naloxone arterial baroreceptor reflex sensitivity mean arterial pressure heart rate
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- 3.Palier MS, et al. Role of angiotensin II, α-adrenergic system and argine vasopressin on arterial pressure in rats. Am J Physiol 1980; 246: H25–30.Google Scholar
- 9.Jong W, et al. Endorphins and central cardiovascular regulation. Br J Pharmacol 1982; 77: 333.Google Scholar
- 11.Becker H, et al. Role of the baroreceptor-reflex in the mediation of central angiotensin II administration. Clin Exper Hypertens 1984, A6: 859–62.Google Scholar
- 12.Lumbers ER, et al. Inhibition of the vagal component of the baroreceptorcardioinhibitory reflex by angiotensin II in dogs and sheep. J Physiol (London) 1983: 336: 83–9.Google Scholar
- 13.Guo GB, et al. Angiotensin II attenuates baroreflex control of heart rate and sympathetic activity. Ara J Physiol 1984; 246: H80–8.Google Scholar