OBJECTIVES Microwaves produce various detrimental changes based on actions of heat or non-specific stress, although the effects of microwaves on pregnant organisms has not been uniform. This study was designed to clarify the effect of exposure to microwaves during pregnancy on endocrine and immune functions. METHODS Natural killer cell activity and natural killer cell subsets in the spleen we...

Endogenous opioid regulation of neurohypophysial and hypothalamo-pituitary-adrenal (HPA) axis hormone secretion in response to forced swimming (90 s in deep water at 19 degrees C) was investigated in virgin and 21-day-pregnant rats. There was no difference in basal plasma oxytocin concentrations between pregnant and virgin rats, but the opioid antagonist, naloxone, increased basal oxytocin secr...

The purpose of this study was to examine the role of the renin-angiotensin system in mediating the hypertension in response to chronic reductions in uterine perfusion pressure (RUPP) in conscious chronically instrumented pregnant rats. Mean arterial pressure was significantly higher in pregnant rats with chronic RUPP (12563.0 mm Hg, P,0.01, n512) than in pregnant rats (10062.3 mm Hg, n517). Pla...

A chronic reduction in uterine perfusion pressure in the pregnant rat is associated with significant elevations in mean arterial pressure, proteinuria, and reductions in kidney function as is chronic nitric oxide blockade, suggesting that nitric oxide deficiency may contribute to the clinical manifestations of preeclampsia. The purpose of this study was to determine whether supplementation with...

We have previously found that the vascular responsiveness to α1-adrenergic agonists is reduced in pregnant rats and enhanced in a rat model of pregnancy-induced hypertension produced by chronic treatment of pregnant rats with the nitric oxide (NO) synthase inhibitor N G-nitro-l-arginine methyl ester (l-NAME). The purpose of this study was to investigate whether the observed changes in vascular ...

The purpose of this study was to examine the role of the renin-angiotensin system in mediating the hypertension in response to chronic reductions in uterine perfusion pressure (RUPP) in conscious chronically instrumented pregnant rats. Mean arterial pressure was significantly higher in pregnant rats with chronic RUPP (125+/-3.0 mm Hg, P<0.01, n=12) than in pregnant rats (100+/-2.3 mm Hg, n=17)....

We have tested the hypothesis that increased gap junctional communication contributes to the augmented endothelium-dependent vasodilation in pregnancy. Contractile force and connexin43 expression were measured in aortic rings from nonpregnant and pregnant rats. Norepinephrine-constricted aortas from pregnant rats were more sensitive to acetylcholine, but not to sodium nitroprusside, compared wi...

CONTEXT Animal models for essential hypertension have been used for understanding the human pathological conditions observed in pregnant hypertensive women. OBJECTIVE To study the possible effects of pregnancy on hypertension and of hypertension on pregnancy in spontaneously hypertensive rats (SHR), and in their normotensive Wistar-Kyoto (WKY) counterparts. TYPE OF STUDY Comparative study u...

IL-6 is elevated in plasma of preeclamptic women, and twofold elevation of plasma IL-6 increases vascular resistance and arterial pressure in pregnant rats, suggesting a role of the cytokine in hypertension of pregnancy. However, whether the hemodynamic effects of IL-6 reflect direct effects of the cytokine on the mechanisms of vascular contraction/relaxation is unclear. The purpose of this stu...

To test the hypothesis that normal volume expansion during pregnancy is impaired during chronic renal failure, we evaluated the effects of 5/6 nephrectomy (Nx) in Sprague-Dawley rats. Partial Nx was produced by ligation of 2/3 renal arteries and contralateral Nx. Control rats had a sham operation. Four weeks later, rats were assigned to nonpregnant (n=6/each) or pregnant groups (n=11 to 12/each...