Pressor action and dipsogenicity induced by angiotensin II and III in rats

Abstract

The primary brain sites responsible for angiotensin-induced pressor action and dipsogenicity in the laboratory rat appear to be located in forebrain circumventricular organs (CVO). Because CVOs have a reduced blood-brain barrier, intracarotid infusion of angiotensin via a brachial arterial catheter results in direct stimulation of these sites. This investigation determined that brachial arterial infusion of angiotensin II (ANG II) into alert free-moving rats resulted in pressor and dipsogenic responses greater than those observed with equivalent doses of angiotensin III (ANG III). However, intracerebroventricular (ICV) injections of ANG II and ANG III yielded equivalent pressor and drinking responses. ICV pretreatment with the specific angiotensin receptor antagonist [Sar1, Ile8]-ANG II significantly reduced ANG II- and ANG III-induced pressor and drinking responses. This inhibition lasted approximately 20 min with recovery at 60-70 min. The results indicate that ICV-administered ANG III is a much more potent ligand than previously determined if the stickiness due to electrical charge of this compound is prevented by appropriate treatment of glassware. The receptor antagonist results encourage the possibility that ANG II and ANG III activate a common central receptor site.

Mass-Spectrometric Identification of a Novel Angiotensin Peptide in Human Plasma

“…15 In addition, Ang II and Ang III cause a similar vascular effect when injected intracerebroventricularly or directly into certain brain regions. 16,17 In the case of Ang II the increase in blood pressure can be inhibited by a selective inhibitor of aminopeptidase A (APA), which mediates the generation of Ang III by the cleavage of the N-terminal aspartate residue of Ang II. 18 These data suggest that the vasoconstrictive effect of Ang II is mediated by Ang III.…”

Evaluation of Metabolically Stabilized Angiotensin IV Analogs as Procognitive/Antidementia Agents

“…When required, an i.c.v. guide cannula (PE-60; Clay Adams, Parsippany, NY) was stereotaxically positioned (model 900; David Kopf Instruments, Tujunga, CA) in the right hemisphere using flat skull coordinates 1.0 mm posterior and 1.5 mm lateral to the bregma (refer to Wright et al, 1985). The guide cannula measured 2.5 cm in overall length and was prepared with a heat bulge placed 2.5 mm from its beveled tip, thus acting as a stop to control the depth of penetration at 2.5 mm.…”

Leucine aminopeptidase M-induced reductions in blood pressure in spontaneously hypertensive rats.

“…Each rat was initially injected with diazepam (2.5 mg/kg, Parke-Davis, Morris Plains, New Jersey) followed 10 minutes later with ketamine (100 mg/kg, Bristol-Myers Co., New York, New York) and prepared with a left femoral artery catheter (PE-50, Clay Adams, Parsippany, New Jersey) and an intracerebroventricular guide cannula stereotaxically positioned just above the roof of the right lateral ventricle as previously described. 9 Blood pressure and heart rate measurements were monitored via the femoral artery catheter connected to Gould transducers (model P23Id, Gould Statham, Oxnard, California) and a Grass Instruments polygraph (model 7b, Grass Instr. Co., Quincy, Massachusetts) equipped with a Grass tachygraph (model 7P4h).…”