A Study by Continuous Microperfusion of Water and Electrolyte Movements in the Loop of Henle and Distal Tubule of the Rat

Morgan, T. O.; Berliner, Robert W.

doi:10.1159/000179741

Cited by 128 publications

(56 citation statements)

References 7 publications

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“…Similarly, at the early distal micropuncture site, measurements of absolute total C02, chloride, and volume reabsorption were increased after ANF administration. Again, the slight decline in fractional solute and volume reabsorptive rates (e.g., the decrease in fractional chloride reabsorption from 0.96±0.01 to 0.91±0.01, P < 0.005) was consistent with the normal response to increased flow by loop transport processes (23,24).…”

Section: Resultssupporting

confidence: 64%

Renal mechanism of action of rat atrial natriuretic factor.

et al. 1985

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There has been conflict as to whether crude extracts of atrial natriuretic factor increase renal solute excretion by a hemodynamic mechanism or by direct inhibition of tubular transport. To investigate this issue, seven rats were studied during a euvolemic control period and following continuous administration of pure, synthetic 24 amino acid atrial natriuretic factor. A 10-25-fold increase in urinary sodium and chloride excretion occurred with a brisk kaliuresis but little bicarbonaturia. Atrial natriuretic factor caused whole kidney glomerular filtration rate to increase from 1.17±0.04 to 1.52±0.07 ml/min (P < 0.005). A parallel increase in single nephron glomerular filtration rate, from 34±1 to 44±2 nl/min (P < 0.001), and from 26±1 to 37±2 nl/min (P < 0.005) was measured at the end-proximal and early distal nephron sites, respectively. Appropriate for the higher flows were an increase in absolute proximal and loop reabsorptive rates for bicarbonate, chloride, and water, with a slight decrease in fractional solute and volume reabsorption in proximal and loop segments. To exclude the possibility that atrial natriuretic factor increased filtration rate only in anesthetized animals, eight unanesthetized rats were studied. Glomerular filtration rate increased by 45%, from 2.04±0.17 to 2.97±0.27 ml/min (P < 0.005) without significant change in renal plasma flow, as reflected by 14C-para-aminohippurate clearance (5.4±0.5-5.6±0.9 ml/min). The clearance and micropuncture data did not preclude changes in relative blood flow distribution to or in transport by deep nephron segments. In conclusion, atrial natriuretic factor appears to increase renal solute excretion predominantly by a hemodynamic mechanism without directly inhibiting superficial tubular transport.

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Section: Resultssupporting

confidence: 64%

Renal mechanism of action of rat atrial natriuretic factor.

et al. 1985

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“…Borenstein et al (1983) reported that injection of atrial extract into anesthetized rats increased total and medullary blood flow in the kidney. In the present study, the prolonged kaliuresis was accompanied by the diuresis, which suggests that urine flow into the distal tubule may have increased after the injection of a-hANP, since it has been shown that potassium secretion is increased when flow into the distal tubule is increased (Malnic et al 1966;Morgan and Berliner 1969;Kunau et al 1974; Khuri et al 1975;Reineck et al 1975;Diezi et al 1976). This increase in urine flow into the distal tubule could have been elicited by the dissipation of corticomedullary osmotic gradient by medullary washout.…”

Section: Resultssupporting

confidence: 58%

The effects of intravenous injection of .ALPHA.-human atrial natriuretic polypeptide on blood pressure, renal hemodynamics and urinary kinin excretion in anesthetized rabbits.

Nushiro

Abe

Seino

et al. 1987

Tohoku J. Exp. Med.

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Studies were performed in anesthetized rabbits to examine the effects of a-human atrial natriuretic polypeptide (a-hANP) on blood pressure, renal hemodynamics and urinary kinin excretion. Intravenous bolus injection of a-hANP at a dose of 5pg resulted in a transient increase in renal blood flow from 26.6+2.2 to 33.7+2.2 ml/min (p <0.05) and a decrease in mean arterial pressure from 113+1.8 to 107±2.2mmHg (p< 0.01). The calculated renal vascular resistance decreased from 4.50+0.34 to 3.28+0.20 mmHg/ml/min (p <0.05). This vasodilatory effect of a-hANP was immediate and lasted for 30 min. These hemodynamic alterations were not associated with the changes in glomerular filtration rate estimated by creatinine clearance. Intravenous injection of a-hANP also produced marked increases in urine volume from 1.99+0.43 to 5.7+1.20 ml 10 min (p <0.01), urinary sodium from 42.2± 7.6 to 243±54 ,u Eq/ 10 min (p <0.01), urinary potassium from 37.5± 5.5 to 74.8± 10.3 ,u Eq/ 10 min (p <0.01), and urinary kinin excretion from 3.44± 0.49 to 5.26±0.82 ng/ 10 min (p <0.05). The observed natriuretic effect of ahANP lasted only for 30 min, whereas diuretic and kaliuretic effects were sustained for 120 min. Hematocrit levels did not change significantly throughout the experiment. These results indicate that a-hANP is a potent vasodilator substance and that the natriuretic effect induced by the bolus injection of a-hANP is mediated mainly through its renal vasodilatory action. It is also suggested that the renal kinin, at least in part, contributes to the natriuretic effect of a-hANP. a-human atrial natriuretic polypeptide (a-hANP) ; renal hemodynamics ; fluid and electrolyte excretion ; urinary kinin excretion It is well informed that mammalian atrial extract when administered to rats produces a marked natriuresis and diuresis (de Bold et al. 1981;

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“…However, when tubules were perfused with solution 3, volume absorption was inhibited by (19). Effect of metabolic alkalosis.…”

Section: Resultsmentioning

confidence: 99%

Effects of extracellular fluid volume and plasma bicarbonate concentration on proximal acidification in the rat.

Alpern¹,

Cogan²,

Rector³

1983

J. Clin. Invest.

103

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A B S T R A C T The effects of systemic bicarbonate concentration and extracellular fluid volume status on proximal tubular bicarbonate absorption, independent of changes in luminal composition and flow rate, were examined with in vivo luminal microperfusion of rat superficial proximal convoluted tubules. Net bicarbonate absorption and bicarbonate permeability were measured using microcalorimetry. From these data, net bicarbonate absorption was divided into two parallel components: proton secretion and passive bicarbonate diffusion.The rate of net bicarbonate absorption was similar in hydropenic and volume-expanded rats when tubules were perfused with 24 mM bicarbonate, but was inhibited in volume-expanded rats when tubules were perfused with 5 mM bicarbonate. Volume expansion caused a 50% increase in bicarbonate permeability, which totally accounted for the above inhibition. The rate of proton secretion was unaffected by volume expansion in both studies.The rate of net bicarbonate absorption was markedly inhibited in alkalotic expansion as compared with isohydric expansion. Bicarbonate permeabilities were not different in these two conditions, and the calculated rates of proton secretion were decreased by >50% in alkalosis. Net bicarbonate absorption was stimulated in acidotic rats compared to hydropenic rats. This stimulation was attributable to a 25% increase in the rate of proton secretion.We conclude that (a) proton secretion is stimulatedPortions of this study were presented at the 13th, 14th, and 15th Annual Meetings of the American Society of Nephrology and were published in abstract

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A Study by Continuous Microperfusion of Water and Electrolyte Movements in the Loop of Henle and Distal Tubule of the Rat

Cited by 128 publications

References 7 publications

Renal mechanism of action of rat atrial natriuretic factor.

Renal mechanism of action of rat atrial natriuretic factor.

The effects of intravenous injection of .ALPHA.-human atrial natriuretic polypeptide on blood pressure, renal hemodynamics and urinary kinin excretion in anesthetized rabbits.

Effects of extracellular fluid volume and plasma bicarbonate concentration on proximal acidification in the rat.

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