Renal and hormonal effects of water deprivation in late-term pregnant rats.
Water-retaining hormones are stimulated during pregnancy allowing normal volume expansion. Because pregnant rats actively retain water, we postulate that water deprivation (WD) would cause a greater reduction in plasma volume in pregnant than in nonpregnant rats. To test this hypothesis, Sprague-Dawley pregnant and nonpregnant rats were water-deprived for 48 hours. At day 19 of pregnancy, or in the corresponding day in nonpregnant rats, they were randomly assigned to either a WD or a control (C) pair-fed group (n=10 to 12 per group). WD significantly reduced body weight, food intake, and creatinine clearance, and increased urinary osmolality in nonpregnant and pregnant rats. WD reduced plasma volume in a similar proportion in nonpregnant and pregnant rats (nonpregnant rats C=13.1+/-0.4, WD=11.0+/-0.2; pregnant rats C=19.4+/-0.7, WD=16.8+/-0.5 mL, P<0.001). Both groups of pregnant rats had a similar reduction in blood pressure. Plasma renin activity (nonpregnant rats C=6.1+/-1.1, WD=20.5+/-2.0; pregnant rats C=49+/-9.7, WD=94+/-12 ng angiotensin I/mL per hour, P<0.001) and plasma aldosterone levels were increased by pregnancy and further increased by WD. WD significantly reduced urinary kallikrein. WD caused a significant reduction in fetal but not placental weights. Present data indicate that 48-hour WD reduced renal kallikrein and further stimulated water-retaining hormones. We speculate that these are compensatory changes contributing to the maintenance of pregnancy in response to WD.
Salas
Sofía P
SP
Center for Medical Research, School of Medicine, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, PO Box 114-D, Santiago, Chile. ssalas@med.puc.cl
Giacaman
Andrea
A
Vío
Carlos P
CP
D000450:Aldosterone / Q000097:blood / Q000378:metabolism*; D000818:Animals; D001127:Arginine Vasopressin / Q000097:blood / Q000378:metabolism*; D001724:Birth Weight; D001810:Blood Volume; D001834:Body Water / Q000378:metabolism; D003404:Creatinine / Q000097:blood / Q000652:urine; D003681:Dehydration / Q000503:physiopathology*; D004231:Diuresis / Q000502:physiology; D004435:Eating; D005260:Female; D005333:Fetus / Q000473:pathology; D006400:Hematocrit; D007610:Kallikreins / Q000652:urine; D007668:Kidney / Q000503:physiopathology*; D008657:Metabolic Clearance Rate; D009929:Organ Size; D009994:Osmolar Concentration; D010920:Placenta / Q000473:pathology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000503:physiopathology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012083:Renin / Q000097:blood; D012084:Renin-Angiotensin System / Q000502:physiology; D014556:Urine / Q000737:chemistry; D014664:Vasodilation; D014868:Water Deprivation / Q000502:physiology*
D001127:Arginine Vasopressin; D000450:Aldosterone; D003404:Creatinine; D007610:Kallikreins; D012083:Renin