Hypothalamic beta 2-adrenoceptor control of renal sympathetic nerve activity and urinary sodium excretion in conscious, spontaneously hypertensive rats.

Abstract

SUMMARY. The contributions of /Si-, B^-, and a 2 -adrenoceptors in the posterior hypothalamus to the increased renal sympathetic nerve activity and decreased urinary sodium excretion resulting from environmental stress (air jet) in conscious spontaneously hypertensive rats were examined. Air stress increased mean arterial pressure and renal sympathetic nerve activity (54% from 7.0 ± 0.7 integrator resets/min), and decreased urinary sodium excretion (44% from 2.7 ± 0.4 ^Eq/min per 100 g body weight). After bilateral injection of ICI 118,551 OS2-adrenoceptor antagonist) into the posterior hypothalamus of the same spontaneously hypertensive rats, air stress had no effect on renal sympathetic nerve activity (8% from 4.8 ± 0.7 integrator resets/min) or urinary sodium excretion (2% from 5.2 ± 0.8 /lEq/min per 100 g body weight), but still increased mean arterial pressure. Bilateral injection of isoproterenolol (/9-adrenoceptor agonist) into the posterior hypothalamus enhanced the renal sympathetic nerve activity and urinary sodium excretion (but not mean arterial pressure) responses to air stress. Air stress had no effect on renal sympathetic nerve activity or urinary sodium excretion when ICI 118,551 was given into the posterior hypothalamus before isoproterenol. Atenolol (/Ji-adrenoceptor antagonist) had no effect on the renal responses to air stress when given alone or before isoproterenol. Similarly, ICI 118,551 administered into the lateral hypothalamus or lateral cerebral ventricle, or guanabenz (a 2 -adrenoceptor agonist) given into the posterior hypothalamus, had no effects on the renal or mean arterial pressure responses to air stress. Thus, /3 2 -adrenoceptors in the posterior hypothalamus mediate the increased renal sympathetic nerve activity and antinatriuresis resulting from environmental stress in conscious spontaneous hypertensive rats. (Circ Res 58: 241-248, 1986)

Sympathetic activation increases basilar arterial blood flow in normotensive but not hypertensive rats

“…For example, we have demonstrated that sympathetic presynaptic ␤ 2 -adrenoceptor-mediated facilitation of neurogenic pressor response in mesenteric arteries is enhanced in 4-wk-old prehypertensive SHR (52). Also, ␤ 2 -adrenoceptors in the posterior hypothalamus are actively involved in mediating the increased renal sympathetic nerve activity and antinatriuresis resulting from environmental stress in maintaining hypertension in 16wk-old conscious SHR (25). These results suggest that the blunted responses in hypertensive animals are not likely due to dysfunction of ␤ 2 -adrenoceptors on nitrergic nerve terminals.…”

Effects of β1 and β2-Adrenoceptor Agonists Applied into the Hypothalamic Paraventricular Nuclei of Spontaneously Hypertensive Rats on Urine Production

“…It must be neu ronal, since there is some information to support this hypothesis. For instance, electrophysiological studies have suggested that hypothalamic nuclei neuronally influence the kidney to increase reabsorption of water (30,31). Koepke et al (31) suggest that the antidiuretic effect of a (32-agonist injected into the posterior hypothalamus was due to increased activity of renal sympathetic neu rons.…”

PET Imaging of Beta-Adrenoceptors in Human Brain: A Realistic Goal or a Mirage?

“…Cerebral ß-adrenoceptors are involved in several physiological functions, such as respiratory [12,81], cardiovascular [231] and renal [132] sympathetic nervous control. Furthermore, ß-adrenoceptors located on glial cells regulate (injuryinduced) astrogliosis and microglial proliferation [224,85,104,83].…”