Sex differences in pressure diuresis/natriuresis in rabbits

Evans, Roger G.; Stevenson, Kathleen M.; Bergström, Göran; Denton, Kate M.; Madden, Anna C; Gribben, R L; Weekes, Simon R; Anderson, Warwick

doi:10.1046/j.1365-201x.2000.00749.x

Cited by 23 publications

(14 citation statements)

References 22 publications

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“…In the current study, for the first time, we report that renal blood flow is reduced by ϳ35% in the 2K-1W model and ϳ53% in the 2K-2W model, confirming that these rabbit models of maternal hypertension are associated with renal dysfunction. We also report that in late gestation, renal blood flow in the pregnant normotensive rabbit was 8.3 ml·min Ϫ1 ·g Ϫ1 , a level that is double that of RBF (ϳ4 ml·min Ϫ1 ·g Ϫ1 ) in nonpregnant female rabbits (17). This greater renal blood flow in the pregnant rabbit is consistent with human studies that have shown a doubling in renal plasma flow throughout pregnancy (46).…”

Section: Discussionsupporting

confidence: 79%

Chronic maternal hypertension characterized by renal dysfunction is associated with reduced placental blood flow during late gestation in rabbits

McArdle

Roberts

Maduwegedera

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

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Maternal hypertension associated with renal disease is a common pregnancy complication. Previously, we have shown in a rabbit model of mild hypertension that offspring from hypertensive mothers have increased blood pressure as adults. In human pregnancy, hypertension has been associated with decreased utero-placental blood flow. The aim of this study was to determine placental blood flow (PBF) in mild (2-kidney-1-wrapped; 2K-1W) and moderate (2-kidney-2-wrapped; 2K-2W) rabbit models of maternal hypertension. We hypothesized that PBF would be inversely related to the severity of the hypertension. PBF and renal blood flow (RBF) were measured using microspheres on day 28 of a 32-day gestation, in normotensive (sham), 2K-1W, and 2K-2W hypertensive groups. Mean arterial pressure (MAP, approximately 7 mmHg, P < 0.05) was increased, and RBF ( approximately 35%, P < 0.05) was reduced in the 2K-1W and 2K-2W (MAP approximately 20 mmHg, P < 0.01; RBF approximately 53%, P < 0.05) groups compared with the sham group. In the 2K-1W group, PBF fell by approximately 12% (P = 0.08) and fetal-to-placental weight ratio increased by approximately 12% (P < 0.01) compared with the sham group, reflecting an increase in the functional capacity of the placenta to deliver nutrients to the fetus. In the 2K-2W group, PBF decreased approximately 51% (P < 0.05) compared with the sham group, without changes in placental efficiency. Thus, in late gestation, placental blood flow was significantly reduced in the moderate hypertension group, without accompanying changes in fetal or placental weight or placental efficiency. In contrast, mild hypertension resulted in an increase in placental efficiency, without significant changes in placental blood flow. These findings suggest that mild and moderate hypertension may alter placental delivery of nutrients via differing mechanisms dependent upon the severity of the hypertension.

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Section: Discussionsupporting

confidence: 79%

Chronic maternal hypertension characterized by renal dysfunction is associated with reduced placental blood flow during late gestation in rabbits

McArdle

Roberts

Maduwegedera

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

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“…There was, however, no effect on long-term blood pressure. 12 Furthermore, gender-specific difference in renal responses to Ang II have been demonstrated in humans. 22 These results suggest that there are differences in normal male and female renal function, and therefore, an adverse intrauterine environment may have different effects in males and females such that long-term blood pressure regulation is altered.…”

Section: Discussionmentioning

confidence: 99%

“…12 MAP was continuously recorded for 30 minutes, with the mean of the final 15 minutes taken as the conscious resting pressure.…”

Section: Measurement Of Mapmentioning

confidence: 99%

Adult Rabbit Offspring of Mothers With Secondary Hypertension Have Increased Blood Pressure

et al. 2003

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Abstract-Preexisting chronic hypertension complicates up to 5% of pregnancies and is associated with an increased risk of low-birth-weight babies. Studies suggest that an adverse intrauterine environment leading to low birth weight is linked to an increased risk of cardiovascular disease, including hypertension, in the adult. In this study, the blood pressure of offspring from mothers with hypertension were followed up into adulthood. Two-kidney, 1-wrapped hypertension was induced in 7 female rabbits; 5 other rabbits underwent sham surgery. Four weeks later, rabbits were mated, at which time mean arterial pressure was 118Ϯ3 and 87Ϯ5 mm Hg in the hypertensive and sham groups, respectively (PϽ0.001). The blood pressure of 30-week-old females was 89Ϯ2 mm Hg in the offspring of hypertensive (nϭ14) and 79Ϯ1 mm Hg in the offspring of normotensive (nϭ13) mothers (PϽ0.005). Also, plasma renin activity was significantly lower in the female offspring of hypertensive mothers at 10 weeks of age (PϽ0.05), suggesting that development of the renin-angiotensin system was altered. In contrast, male offspring from hypertensive and normotensive mothers had similar mean arterial pressure and plasma renin activity. In conclusion, maternal secondary hypertension can "program" hypertension in female adult offspring. The results also suggest that there are gender-specific differences in sensitivity to altered in utero environmental influences. Key Words: blood pressure Ⅲ rabbits Ⅲ hypertension, secondary Ⅲ pregnancy Ⅲ renin Ⅲ gender H ypertension is the most common complication associated with pregnancy. 1 Preexisting chronic hypertension complicates up to 5% of pregnancies and is associated with an increased risk of preterm labor, uteroplacental insufficiency, placental detachment, and low birth weight. 2,3 In the United States, the percentage of mothers older than 30 years increased from 16% in 1976 to 37% in 2001 4,5 ; it is also known that the rate of hypertension increases in women Ͼ30 years of age. 6 It is therefore predicted that the incidence of chronic hypertension during pregnancy will increase in association with this trend toward childbearing at older ages. Epidemiological studies suggest that an adverse intrauterine environment leading to low birth weight is linked to an increased risk of cardiovascular disease, including hypertension, in the adult. 7,8 Even mild chronic hypertension during pregnancy has been associated with low birth weight. 2,3 We have therefore investigated the effect of chronic hypertension during pregnancy on the blood pressure of adult offspring. To this end, secondary hypertension was induced in female rabbits, these rabbits were mated, and then the blood pressure of their offspring was followed up into adulthood. The adult offspring were also subjected to the prohypertensive physiological challenges of an increased salt diet and weight gain.

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“…Rabbits were meal fed and provided with water ad libitum [10]. All experiments were approved in advance by the Monash University Department of Physiology/Central Animal Services Animal Ethics Committee and were performed in accordance with the Australian Code of Practice for the Care and Use of Animals for Scientific Purposes.…”

Section: Animalsmentioning

confidence: 99%

Prostaglandins and nitric oxide in regional kidney blood flow responses to renal nerve stimulation

Rajapakse

Flower

Eppel

et al. 2004

Pflugers Arch - Eur J Physiol

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We examined the roles of cyclooxygenase products and of interactions between the cyclooxygenase and nitric oxide systems in the mechanisms underlying the relative insensitivity of medullary perfusion to renal nerve stimulation (RNS) in anaesthetized rabbits. To this end we examined the effects of ibuprofen and N(G)-nitro-L: -arginine (L-NNA), both alone and in combination, on the responses of regional kidney perfusion to RNS. Under control conditions, RNS produced frequency-dependent reductions in total renal blood flow (RBF; -82+/-3% at 6 Hz), cortical laser-Doppler flux (CLDF; -84+/-4% at 6 Hz) and, to a lesser extent, medullary laser-Doppler flux (MLDF; -46+/-7% at 6 Hz). Ibuprofen did not affect these responses significantly, suggesting that cyclooxygenase products have little net role in modulating renal vascular responses to RNS. L-NNA enhanced RBF (P=0.002), CLDF (P=0.03) and MLDF (P=0.03) responses to RNS. As we have shown previously, this effect of L-NNA was particularly prominent for MLDF at RNS frequencies < or = 1.5 Hz. Subsequent administration of ibuprofen, in L-NNA-pretreated rabbits, did not affect responses to RNS significantly. We conclude that counter-regulatory actions of NO, but not of prostaglandins, partly underlie the relative insensitivity of medullary perfusion to renal nerve activation.

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Sex differences in pressure diuresis/natriuresis in rabbits

Cited by 23 publications

References 22 publications

Chronic maternal hypertension characterized by renal dysfunction is associated with reduced placental blood flow during late gestation in rabbits

Chronic maternal hypertension characterized by renal dysfunction is associated with reduced placental blood flow during late gestation in rabbits

Adult Rabbit Offspring of Mothers With Secondary Hypertension Have Increased Blood Pressure

Prostaglandins and nitric oxide in regional kidney blood flow responses to renal nerve stimulation

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