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A chromosome 1 blood pressure quantitative trait locus (QTL) was introgressed from the stroke-prone spontaneously hypertensive rats (SHRSP) to Wistar-Kyoto (WKY) rats. This congenic strain (WKYpch1.0) showed an exaggerated pressor response to both restraint and cold stress. In this study, we evaluated cardiovascular and sympathetic response to an air-jet stress and also examined the role of the brain renin-angiotensin system (RAS) in the stress response of WKYpch1.0. We measured mean arterial pressure (MAP), heart rate (HR), and renal sympathetic nerve activity (RSNA) responses to air-jet stress in WKYpch1.0, WKY, and SHRSP. We also examined effects of intracerebroventricular administration of candesartan, an ANG II type 1 receptor blocker, on MAP and HR responses to air-jet stress. Baseline MAP in the WKYpch1.0 and WKY rats were comparable, while it was lower than that in SHRSP rats. Baseline HR did not differ among the strains. In WKYpch1.0, air-jet stress caused greater increase in MAP and RSNA than in WKY. The increase in RSNA was as large as that in SHRSP, whereas the increase in MAP was smaller than in SHRSP. Intracerebroventricular injection of a nondepressor dose of candesartan inhibited the stress-induced pressor response to a greater extent in WKYpch1.0 than in WKY. Intravenous injection of phenylephrine caused a presser effect comparable between WKYpch1.0 and WKY. These results suggest that the chromosome 1 blood pressure QTL congenic rat has a sympathetic hyperreactivity to an air-jet stress, which causes exaggerated pressor responses. The exaggerated response is at least partly mediated by the brain RAS. [ABSTRACT FROM AUTHOR]

Presents a study which examined the effects of clonidine injected unilaterally into the rostral ventrolateral medulla of conscious, unrestrained rats. Methods; Results; Discussion.

Presents information on a study that investigated whether inhibition of brain nitric oxide synthase elevates blood pressure and whether this elevation is enhanced by salt loading. Methodology used in the study; Effect of chronic intracerebroventricular infusion of ...-monomethyl-L-arginine on blood pressure and body weight; What the results indicate.

Examines the effects of clonidine delivered to the caudal ventrolateral medulla (CVLM) and the contribution of endogenous alpha-adrenoceptor-mediated mechanisms to the tonic activities of the CVLM neurons. Methodology of the study; Physiological effects of clonidine; Conclusions of the study.