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.
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
Sofía P
SP
Salas
Andrea
A
Giacaman
Carlos P
CP
Vío
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