Effect of hypothermia on baroreflex control of heart rate and renal sympathetic nerve activity in anaesthetized rats

Heart rate (HR) and renal sympathetic nerve activity (RSNA) responses to ramp changes in blood pressure (BP) by (de)pressor agents and to acute volume expansion were recorded in conscious young, mature, and old Wistar rats maintained for 4 wk on diets containing low, control, or high dietary Na. Both HR and RSNA responses to BP increases or decreases were attenuated on low-Na diet compared with control Na diet. On high-Na diet, HR responses to BP changes and RSNA responses to BP increases were also attenuated, but in contrast the excitatory response of RSNA to BP decreases was augmented. The inhibitory RSNA response, but not the HR response, to volume expansion was significantly attenuated in young rats on high-Na diet but not on low-Na diet. The effects of both low and high dietary Na on HR and RSNA responses were most marked in young rats, less in mature rats, and even less in old rats. These results indicate a discordance of high dietary Na-induced changes in HR vs. RSNA control by the arterial and cardiopulmonary baroreflex, which is suggestive of central mechanisms affected by dietary Na. The developing nervous system appears to be the most responsive to dietary Na.

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Baroreflex control of heart rate and renal sympathetic nerve activity in rats with low brain angiotensinogen

Neuropeptides ◽

10.1016/j.npep.2007.12.003 ◽

2008 ◽

Vol 42 (2) ◽

pp. 159-168 ◽

Cited By ~ 11

Author(s):

Sordaini M. Caligiorne ◽

Ana Quênia G. Silva ◽

Marco A.P. Fontes ◽

Jose R. Silva ◽

Ovidiu Baltatu ◽

...

Keyword(s):

Heart Rate ◽

Sympathetic Nerve ◽

Sympathetic Nerve Activity ◽

Nerve Activity ◽

Baroreflex Control ◽

Renal Sympathetic Nerve Activity ◽

Renal Sympathetic Nerve ◽

Renal Sympathetic

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Cardiovascular and neurohormonal effects of intravenous adrenomedullin in conscious rabbits

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1995.269.5.r1289 ◽

1995 ◽

Vol 269 (5) ◽

pp. R1289-R1293 ◽

Cited By ~ 11

Author(s):

M. Fukuhara ◽

T. Tsuchihashi ◽

I. Abe ◽

M. Fujishima

Keyword(s):

Heart Rate ◽

Mean Arterial Pressure ◽

Arterial Pressure ◽

Sympathetic Nerve ◽

Sympathetic Nerve Activity ◽

Nerve Activity ◽

Renal Sympathetic Nerve Activity ◽

Renal Sympathetic Nerve ◽

Conscious Rabbits ◽

Renal Sympathetic

Adrenomedullin is a vasodilative peptide and shows slight homology with calcitonin gene-related peptide. In the present study, we investigated the effects of adrenomedullin on cardiovascular and neurohormonal responses in 13 conscious rabbits. The animals were chronically instrumented with bipolar electrodes on the left renal sympathetic nerve. Intravenous administration of human adrenomedullin (10, 100, 1,000, and 3,000 pmol/kg, n = 6) caused a dose-dependent reduction in mean arterial pressure (0 +/- 2, -1 +/- 2, -19 +/- 2, and -29 +/- 4 mmHg, respectively) concomitant with increases in heart rate, renal sympathetic nerve activity, plasma renin activity, and plasma norepinephrine. The significant reduction in mean arterial pressure induced by 1,000 pmol/kg of adrenomedullin occurred within 1 min after injection and lasted for 15 min (n = 7). In contrast, the significant increases in heart rate and renal sympathetic nerve activity lasted for more than 50 min. When mean arterial pressure was decreased by 15 mmHg by adrenomedullin, the increases in heart rate and renal sympathetic nerve activity were 53 +/- 8 beats/min and 78 +/- 13%, respectively, which were significantly smaller than those induced by intravenous injection of sodium nitroprusside (102 +/- 14 beats/min and 155 +/- 34%, respectively). These results suggest that intravenous adrenomedullin exerts a hypotensive action that is associated with the attenuated reflex-mediated sympathetic activation.

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