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Brazilian Journal of Medical and Biological Research
On-line version ISSN 1414-431X
Functional evidence that the central renin-angiotensin system plays a role in the pressor response induced by central injection of carbachol. Braz J Med Biol Res [online]. 1997, vol.30, n.4, pp. 493-496. ISSN 1414-431X. http://dx.doi.org/10.1590/S0100-879X1997000400010.
We investigated the effects of losartan, an AT1-receptor blocker, and ramipril, a converting enzyme inhibitor, on the pressor response induced by angiotensin II (ANG II) and carbachol (a cholinergic receptor agonist). Male Holtzman rats (250-300 g) with a stainless steel cannula implanted into the lateral ventricle (LV) were used. The injection of losartan (50 nmol/1 µl) into the LV blocked the pressor response induced by ANG II (12 ng/1 µl) and carbachol (2 nmol/1 µl). After injection of ANG II and carbachol into the LV, mean arterial pressure (MAP) increased to 31 ± 1 and 28 ± 2 mmHg, respectively. Previous injection of losartan abolished the increase in MAP induced by ANG II and carbachol into the LV (2 ± 1 and 5 ± 2 mmHg, respectively). The injection of ramipril (12 ng/1 µl) prior to carbachol blocked the pressor effect of carbachol to 7 ± 3 mmHg. These results suggest an interaction between central cholinergic pathways and the angiotensinergic system in the regulation of arterial blood pressure
Keywords : pressor response; central angiotensin; carbachol.