Effects of Fasting on Uterine Blood Flow and Substrate Uptake in Sheep

Morriss, Frank H.; Rosenfeld, Charles R.; Crandell, Sharon S.; Adcock, Eugene W.

doi:10.1093/jn/110.12.2433

Cited by 50 publications

(25 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In contrast, a 9% decrease in blood pressure was observed by the fifth day of fasting, a change that was similar to what we observed in group 2a animals by the third day. One major difference between the present study and that of Morriss et al 26 was the difference in the provision of calcium in the drinking water. We used deionized water that contained no calcium.…”

Section: Discussioncontrasting

confidence: 77%

See 1 more Smart Citation

Hypocalcemia and pregnancy-induced hypertension produced by maternal fasting.

Prada¹,

Ross²,

Clark³

1992

Hypertension

View full text Add to dashboard Cite

During pregnancy, maternal calcium needs increase as a result of increasing calcium requirements for fetal bone development. These needs have to be completely supplied by the mother via placental transfer. Several studies link low serum ionized calcium concentrations with the development of hypertension and pregnancy-induced hypertension. We hypothesized that maternal hypocalcemia would develop concomitantly with the development of hypertension in sheep that were fasted in late gestation. Sixteen instrumented ewes were used in the present study. After a 2-day baseline period, food was withdrawn from 10 animals in the experimental group (group 2) for 3 days, whereas the remaining six were allowed to eat and drink normally (group 1). Blood pressure, uteroplacental blood flow, and heart rate were monitored daily. Fasted animals were given deionized water (calcium free) to drink, whereas control animals were given tap water containing 32.9 mg/1 calcium concentration. Based on the analysis of the ionized calcium concentration response to fasting, group 2 animals were placed in one of two groups: hypocalcemia did not develop in group 2a, whereas in group 2b the ionized calcium concentration decreased 27% (from 1.09±0.07 to 0.80±0.06 mM,p=0.01) by the third day of fasting. Group 2b responded with a 16% elevation in maternal blood pressure (p=0.01) and a 43% reduction in uteroplacental blood flow. Furthermore, a positive correlation was found between maternal and fetal blood ionized calcium concentrations (r=0.860). The intravenous infusion of calcium gluconate to the animals in group 2b resulted in a significant (p=0.05) recovery of blood ionized calcium concentration, reduction of blood pressure, and recovery of uteroplacental blood flow. The results of the present study are interpreted to suggest that altered calcium concentrations during the last trimester of multiple ovine pregnancy may play an important role in the development of pregnancy-induced hypertension. (Hypertension 1992;20:620-626) KEY WORDS • hypocalcemia • fasting • sheep • hypertension, pregnancy-induced N umerous explanations have been proposed to account for the development of pregnancyinduced hypertension, including incompatibilities between the maternal and fetal blood types, high salt (NaCl) intake, calcium deficiency, poor general nutrition, changes in the renin-angiotensin system, and a predisposed genetic make-up. 1 -7 In humans, pregnancy-induced hypertension is a hypertensive disorder peculiar to pregnancy that usually develops between the 30th week of pregnancy and the end of the first week postpartum. If associated with albuminuria, edema, or both, the disorder is termed preeclampsia. 8 The etiology of pregnancy-induced hypertension is still unknown: it develops in 10-15% of pregnant women and characteristically occurs in young primigravidas 9 and women with preexisting hypertension or vascular disease. 10Several recent studies have linked hypocalcemia and high blood pressure.

show abstract

Section: Discussioncontrasting

confidence: 77%

“…Previously, Morriss et al 26 have reported the effect of 5 days of fasting in late gestation ewes. In those studies, in which regular tap water was provided to the animals, none of the four pregnant animals recorded developed hypertension.…”

Section: Discussionmentioning

confidence: 99%

Hypocalcemia and pregnancy-induced hypertension produced by maternal fasting.

Prada¹,

Ross²,

Clark³

1992

Hypertension

View full text Add to dashboard Cite

show abstract

“…Complete fasting in ewes carrying singeltons results in lower concentrations of glucose and amino acids in the maternal blood, a marked reduction in uterine blood flow, and decreases in uterine uptake of glucose and amino acids (Morriss et al, 1980). Undernutrition to 70% of nutrient requirements (National Research Council (NRC), 1985) throughout gestation also reduced maternal and foetal concentrations of blood glucose in singeltons' pregnancies (Edwards and McMillen, 2002).…”

Section: Litter-size-dependent Iugr and Nutritional Insultmentioning

confidence: 99%

Litter-size-dependent intrauterine growth restriction in sheep

Gootwine

Spencer

Bazer

2007

Animal

View full text Add to dashboard Cite

Regulation of foetal development in sheep depends on interactions between the intrinsic capacity of the foetus for growth and the maternal environment. Lambs born in multi-foetus litters have relatively small placentae with fewer cotelydons, and lower birth weights. Litter-size-dependent intrauterine growth restriction (IUGR) is evident at mid gestation when metabolic needs of the conceptus are moderate, and overnutrition of ewes with multiple foetuses does not promote growth of their foetuses to the size of singletons. Those observations suggest that placental and conceptus growth in multi-foetus pregnancies is reprogrammed at mid gestation by an as yet undefined mechanism to attenuate foetal growth. This may protect the foetus from severe nutritional insult during late gestation, when its daily growth rate is at a maximum. In that way, lambs born in large litters with relatively lower birth weights may not experience the long-term physiological insults that can be observed in small lambs born to undernourished ewes.

show abstract

“…It is also becoming increasingly apparent that changes in maternal body composition and diet not only affect fetal growth and development as a result of direct effects on substrate availability to the fetus, but also indirectly through changes in placental growth and function. Maternal undernutrition in experimental animals and human pregnancy has been associated with reduced placental size and reduced blood flow in uterine and umbilical circulation (11,12). Therefore, a component of the asymmetric fetal growth restriction in undernourished pregnancy in humans and animals is due to a reduction in oxygen as well as nutrient delivery to the fetus.…”

mentioning

confidence: 99%

The vulnerable developing brain

Giussani

2011

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Effects of Fasting on Uterine Blood Flow and Substrate Uptake in Sheep

Cited by 50 publications

References 25 publications

Hypocalcemia and pregnancy-induced hypertension produced by maternal fasting.

Hypocalcemia and pregnancy-induced hypertension produced by maternal fasting.

Litter-size-dependent intrauterine growth restriction in sheep

The vulnerable developing brain

Contact Info

Product

Resources

About