Effects of pregnancy on glucose reabsorption by the proximal convoluted tubule in the rat.

Bishop, J H; Green, R

doi:10.1113/jphysiol.1981.sp013907

Cited by 13 publications

(3 citation statements)

References 21 publications

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“…In pregnant rats, similar changes in whole kidney function to those seen in pregnant women have been described (Baylis, 1980a;Bishop & Green, 1980;Atherton & Pirie, 1981;Garland & Green, 1982). The use of the rat also permits the application of renal micropuncture techniques to pregnancy; rats of the Sprague-Dawley (SD) and Munich Wistar (MW) strains (the latter with surface glomeruli) have both been used to extend investigations to the single nephron level (Baylis, 1980a,Z>;Bishop & Green, 1981Garland & Green, 1982).…”

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confidence: 86%

Hormone profiles for progesterone, oestradiol, prolactin, plasma renin activity, aldosterone and corticosterone during pregnancy and pseudopregnancy in two strains of rat: correlation with renal studies

Garland¹,

Atherton²,

Baylis³

et al. 1987

Journal of Endocrinology

127

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Plasma samples were obtained throughout pregnancy and pseudopregnancy from Sprague-Dawley (SD) rats and during pregnancy from rats of the Munich Wistar (MW) strain. The concentrations of progesterone, oestradiol, prolactin, plasma renin activity (PRA), aldosterone and corticosterone were measured by radioimmunoassay to establish hormonal profiles in the two strains of rat. Circulating progesterone concentrations in both strains of rat were significantly higher during pregnancy than in virgin controls, except at term in the SD group. The hormonal pattern for pseudopregnancy was similar to that of the first half of pregnancy. Oestradiol concentrations were similar to, or lower than, those in virgin controls throughout pseudopregnancy and for the first 2 weeks of pregnancy in both strains of rat. Increased concentrations of steroid were seen only in the pregnant groups towards term. In SD rats, highest prolactin concentrations were apparent during the first half of pregnancy and pseudopregnancy, and at term in the pregnant group. Pregnant MW rats showed a different profile for this hormone, with low levels throughout pregnancy except at term. In all groups PRA rose to a peak at day 9 and decreased to day 16. Pregnant SD rats also showed a significant increase at term. Aldosterone concentrations were significantly increased at several stages of pregnancy in both strains of rat, particularly during the second half of gestation. Pseudopregnant animals showed a different hormone profile, with no significant changes until day 16 when lower concentrations were recorded. There was little variation in the circulating corticosterone concentration except in pregnant rats at term when levels fell. These findings are discussed in relation to the known renal changes of pregnancy and pseudopregnancy.

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confidence: 86%

Hormone profiles for progesterone, oestradiol, prolactin, plasma renin activity, aldosterone and corticosterone during pregnancy and pseudopregnancy in two strains of rat: correlation with renal studies

Garland¹,

Atherton²,

Baylis³

et al. 1987

Journal of Endocrinology

127

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“…Although the rat has been used extensively for investigating renal function at the single nephron level in non-pregnant animals there have been only a few reports of single nephron function in pregnant animals, and these invariably deal with one particular aspect, usually at a single stage of pregnancy (Churchill, Bengele & Alexander, 1978; Baylis, 1980;Bishop & Green, 1981). There has been little attempt to determine the mechanisms underlying the changes or the site at which they occur.…”

Section: Introductionmentioning

confidence: 99%

Micropuncture study of changes in glomerular filtration and ion and water handling by the rat kidney during pregnancy

Garland

Green

1982

The Journal of Physiology

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SUMMARY1. In rats receiving 200 gl. min-sodium chloride, glomerular filtration rate, single nephron glomerular filtration rate, and fractional reabsorption were measured at various points along the nephron, and ionic concentrations measured in early distal tubular fluid in virgin and 6, 12 and 19 day pregnant rats.2. Glomerular filtration increased progressively until the twelfth day ofpregnancy. At 19 days of pregnancy the glomerular filtration rate, while still above virgin levels, was reduced below 12 day pregnant levels.3. Single nephron glomerular filtration rates measured in proximal and distal tubules were different at both 12 and 19 days of pregnancy, indicating an alteration of tubuloglomerular feed-back. 4. A change in the ratio ofglomerular filtration rate: distal single nephron filtration rate indicated a redistribution of glomerular filtrate to juxtamedullary nephrons by the sixth day of pregnancy.5. Fluid reabsorption is similar up to the early distal tubule but it is not possible to say whether reabsorption is the same in proximal tubules. More fluid is reabsorbed by late distal tubules and collecting ducts in 12 and 19 day pregnant animals than in the virgin and 6 day pregnant animals.6. Changes in ion reabsorption by the loop of Henle occurred during pregnancy; sodium reabsorption was increased by the sixth day of pregnancy and potassium reabsorption by the twelfth day.

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“…With free flow micropuncture techniques it was, perhaps surprisingly, not possible to demonstrate a defect in proximal tubular mechanisms for glucose reabsorption; indeed when stressed by infusion of glucose the proximal convoluted tubule of pregnant rats was able to reabsorb more glucose than in virgin animals [76]. This offset the increased filtered load of glucose due to an increased GFR and the net result was that in pregnant animals less glucose was delivered out of the proximal convoluted tubule to more distal parts of the nephron than in virgins [77].…”

Section: Glucosementioning

confidence: 95%

Renal Function in Pregnancy

Atherton

Green

1983

Clinical Science

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Although our understanding of many renal mechanisms has been advancing rapidly over the past few years, there is still a dearth of infoimation about changes that occur in renal function during pregnancy -surely one of the greatest physiological disturbances possible. It is difficult in many instances to find a description of the changes that occur quite apart from the underlying alterations in mechanisms that are responsible for them.Part of the difficulty has arisen because of the ethical and methodological problems that arise when women are used as 'experimental animals'; until recently there has not been a suitably documented animal model, though whether this was because of technical difficulties or lack of interest on the part of investigators is not known. Recently, however, it has become apparent that many changes in renal function in the rat are similar to those occurring in women and some aspects of renal function in the rat have been investigated in detail. Since not all aspects of renal function can be covered in this review we shall concentrate on three of the more important areas, namely haemodynamics, sodium and water handling and glucose excretion, and discuss how these are changed during pregnancy; comments on the possible mechanisms involved in these changes are presented where appropriate. HaemodvnamicsIn pregnant women cardiac output increases during the fust trimester and thereafter is maintained. The fall in cardiac output that has been noted towards the end of pregnancy [ 11 is now considered to be due primarily to the posture of the women while the measurements were made [2-41. The Correspondence: Professor R. Green, Department of Physiology, University of Manchester, Manchester M13 9PT, U.K. increased cardiac output is distributed primarily to the skin, uterus, kidneys, breasts and gut [S].The portion of the increased blood flow received by the kidney is out of proportion to its normal flow; cardiac output increases by about 30% but renal plasma flow (RPF) and glomerular fdtration rate (GFR) can increase by 50% or more. There is now good evidence that changes in GFR occur very early during pregnancy, a rise of 45% occurring within the first 9 weeks [6], and that they reach a maximum at the end of the fust trimester and then remain high until the end of pregnancy [7,8]. However, if GFR is measured in late pregnancy with the subject in the supine position [9,10] it is found to have decreased. The position is further confused in that when inulin or creatinine was infused to measure GFR, and the body fluid compartments were expanded with glucose solution, there was no change in GFR late in pregnancy; use of endogenous creatinine clearance, however, showed a fall in GFR [8]. One conflicting study shows evidence that posture has no effect on GFR [ 111, so the role of posture and its effect in late pregnapcy still requires some clarification.Changes in RPF are not as well documented as changes @ IjFR, presumably because they are more difficplt to measure, but the general pattern seems to be simila...

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Effects of pregnancy on glucose reabsorption by the proximal convoluted tubule in the rat.

Cited by 13 publications

References 21 publications

Hormone profiles for progesterone, oestradiol, prolactin, plasma renin activity, aldosterone and corticosterone during pregnancy and pseudopregnancy in two strains of rat: correlation with renal studies

Hormone profiles for progesterone, oestradiol, prolactin, plasma renin activity, aldosterone and corticosterone during pregnancy and pseudopregnancy in two strains of rat: correlation with renal studies

Micropuncture study of changes in glomerular filtration and ion and water handling by the rat kidney during pregnancy

Renal Function in Pregnancy

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