NOS inhibition restores renal responses to atrial  distension during pregnancy

Tam, Siu Lin; Kaufman, Susan

doi:10.1152/ajpregu.00705.2001

Cited by 2 publications

(1 citation statement)

References 24 publications

(31 reference statements)

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“…In pregnant animals, administration of the NOS inhibitor N G -nitro-L-arginine methyl ester (L-NAME) completely restored the appearance of Fos immunoreactivity in both parvo-and magnocellular regions of the PVN, and the resulting natriuresis, in response to atrial distension (187,188). These findings emphasize the potential complexity of endocrine control of baroreflex function in a state such as pregnancy.…”

Section: Roles Of Ang II and No In Baroreflex Modulation During Pregnmentioning

confidence: 80%

Pregnancy and the endocrine regulation of the baroreceptor reflex

Brooks

Dampney

Heesch

2010

American Journal of Physiology-Regulatory, Integrative and Comp

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-The purpose of this review is to delineate the general features of endocrine regulation of the baroreceptor reflex, as well as specific contributions during pregnancy. In contrast to the programmed changes in baroreflex function that occur in situations initiated by central command (e.g., exercise or stress), the complex endocrine milieu often associated with physiological and pathophysiological states can influence the central baroreflex neuronal circuitry via multiple sites and mechanisms, thereby producing varied changes in baroreflex function. During pregnancy, baroreflex gain is markedly attenuated, and at least two hormonal mechanisms contribute, each at different brain sites: increased levels of the neurosteroid 3␣-hydroxydihydroprogesterone (3␣-OH-DHP), acting in the rostral ventrolateral medulla (RVLM), and reduced actions of insulin in the forebrain. 3␣-OH-DHP appears to potentiate baroreflex-independent GABAergic inhibition of premotor neurons in the RVLM, which decreases the range of sympathetic nerve activity that can be elicited by changes in arterial pressure. In contrast, reductions in the levels or actions of insulin in the brain blunt baroreflex efferent responses to increments or decrements in arterial pressure. Although plasma levels of angiotensin II are increased in pregnancy, this is not responsible for the reduction in baroreflex gain, although it may contribute to the increased level of sympathetic nerve activity in this condition. How these different hormonal effects are integrated within the brain, as well as possible interactions with additional potential neuromodulators that influence baroreflex function during pregnancy and other physiological and pathophysiological states, remains to be clearly delineated.3␣-hydroxy-dihydroprogesterone; angiotensin II; insulin; paraventricular nucleus of the hypothalamus NORMAL PREGNANCY is characterized by profound changes in fluid and electrolyte balance and blood pressure regulation. Blood volume and cardiac output increase by 30 -50%, but arterial pressure falls due to even greater decreases in systemic vascular resistance (120,138,189). These hemodynamic alterations are evident early in pregnancy, precede the increases in uterine blood flow, and are sustained until parturition (127,138,189). Considerable data implicate increases in relaxin and nitric oxide (NO) in the systemic vasodilation induced by pregnancy (20,127,128,177,196). In addition, peripheral vascular sensitivity to circulating vasoconstrictors including vasopressin, angiotensin II (ANG II), and norepinephrine (NE) is decreased (50,71,154).Unlike the hemodynamic changes, which likely subserve adequate fetal development, an adverse consequence of normal pregnancy is a marked impairment of the arterial baroreceptor reflex. This change was first noted by Humphreys and Joels (97,98) in an extensive series of studies in anesthetized pregnant rabbits, in which reductions in carotid sinus pressure failed to elicit normal increases in arterial pressure and peripheral vascular resistanc...

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Section: Roles Of Ang II and No In Baroreflex Modulation During Pregnmentioning

confidence: 80%

Pregnancy and the endocrine regulation of the baroreceptor reflex

Brooks

Dampney

Heesch

2010

American Journal of Physiology-Regulatory, Integrative and Comp

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Role of nitric oxide in the natriuretic and diuretic responses in pregnant rats

Khraibi

Tang

2003

American Journal of Physiology-Renal Physiology

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Normal pregnancy is characterized by sodium conservation and increase in plasma volume, yet the natriuretic response to acute saline volume expansion (VE) is intact in pregnant rats. Nitric oxide (NO) has been suggested to play a role in renal and cardiovascular adaptations to normal pregnancy. The objective of this study was to determine the role of NO in the natriuretic and diuretic responses to VE during pregnancy. Infusion of NG-monomethyl-l-arginine (l-NMMA) was used to inhibit NO synthesis. Nine groups of Sprague-Dawley (SD) rats were studied: nonpregnant (NP-VE, n = 7), midterm pregnant (MP-VE, n = 8), and late-term pregnant (LP-VE, n = 7) SD groups that underwent VE alone after a control period; NP-l-NMMA (n = 7), MP-l-NMMA (n = 8), and LP-l-NMMA (n = 7) SD groups that were infused with l-NMMA after a control period; and another three groups of SD rats (NP-VE-l-NMMA, n = 8; MP-VE-l-NMMA, n = 7; and LP-VE-l-NMMA, n = 12) that underwent simultaneous VE and l-NMMA infusion after a control period. The change in fractional excretion of sodium was 7.22 +/- 1.03% for NPVE, 9.89 +/- 1.85% for NP-l-NMMA, and 17.66 +/- 1.85% for NP-VE-l-NMMA (P < 0.05 vs. NP-VE and NP-l-NMMA); 6.61 +/- 1.07% for MP-VE, 7.99 +/- 1.92% for MP-l-NMMA, and 10.24 +/- 1.91% for MP-VE-l-NMMA [not significant (NS) vs. MP-VE and MP-l-NMMA]; 8.20 +/- 1.92% for LP-VE, 8.09 +/- 0.70% for LP-l-NMMA, and 7.57 +/- 1.11% for LP-VE-l-NMMA (both NS vs. LP-VE and LP-l-NMMA). The increase in renal interstitial hydrostatic pressure was significantly greater in all NP compared with pregnant groups with similar experimental intervention (i.e., VE, l-NMMA, or VE-l-NMMA). In conclusion, the natriuretic and diuretic responses to VE and l-NMMA infusion were additive in NP but not in pregnant rats, indicating a possible lower ability of pregnant rats to respond to combined significant natriuretic and diuretic stimuli.

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NOS inhibition restores renal responses to atrial distension during pregnancy

Abstract: . NOS inhibition restores renal responses to atrial distension during pregnancy.

Cited by 2 publications

References 24 publications

Pregnancy and the endocrine regulation of the baroreceptor reflex

Pregnancy and the endocrine regulation of the baroreceptor reflex

Role of nitric oxide in the natriuretic and diuretic responses in pregnant rats

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