Effects of water immersion on renal hemodynamics in normal man

1976 ◽  
Vol 41 (2) ◽  
pp. 230-233 ◽  
Author(s):  
M. Epstein ◽  
R. Levinson ◽  
R. Loutzenhiser
Keyword(s):  
Renal Plasma Flow ◽  
Water Immersion ◽  
Renal Perfusion ◽  
Time Of Day ◽  
Renal Hemodynamics ◽  
Normal Male ◽  
Renal Changes ◽  
Normal Man ◽  
Seated Posture ◽  
Male Subjects

Although previous studies have demonstrated that water immersion to the neck (NI) results in a significant natriuresis and diuresis, the mechanisms are incompletely delineated. Since recent studies have demonstrated that NI induces a marked increase in cardiac index, it is possible that, as a consequence, renal hemodynamics may be augmented markedly during NI thereby mediating the encountered renal changes. The present study was undertaken to delineate the effects of NI on renal plasma flow and glomerular filtration rate as assessed by the clearance of PAH (CPAH) and inulin (CIn), respectively. Nine normal male subjects were studied on two occasions, control and NI. The conditions of seated posture and time of day were identical. Immersion did not alter CIn or CPAH at a time when sodium excretion was increasing markedly. The constancy of CPAH during NI suggests that renal blood flow is unaltered and that the natriuresis of NI is mediated independently of alterations in overall renal perfusion. The sluggish decline of a naturiuresis during recovery is consistent with the presence of a humoral factor contributing to the encountered natriuresis.

Suppression of ADH during water immersion in normal man

1975 ◽  
Vol 38 (6) ◽  
pp. 1038-1044 ◽  
Author(s):  
M. Epstein ◽  
D. S. Pins ◽  
M. Miller
Keyword(s):  
Water Immersion ◽  
Free Water ◽  
Urine Osmolality ◽  
Time Of Day ◽  
Normal Male ◽  
Free Water Clearance ◽  
Water Handling ◽  
Normal Man ◽  
Male Subjects ◽  
Central Hypervolemia

Since previous studies from this laboratory have demonstrated that the redistribution of blood volume and concomitant relative central hypervolemia induced by water immersion to the neck causes a profound natriuresis and a suppression of the renin-aldosterone system, it was of interest to assess whether the diuresis induced by immersion was mediated by an analogous inhibition of ADH. The effects of water immersion on renal water handling and urinary ADH excretion were assessed in 10 normal male subjects studied following 14 h of overnight dehydration on two occasions, control and immersion. The conditions of seated posture and time of day were identical. During control ADH persisted at or above prestudy values. Immersion resulted in a progressive decrease in ADH excretion from 80.1 plus or minus 7 (SEM) to 37.3 plus or minus 6.3 muU/min (P smaller than 0.025). Cessation of immersion was associated with a marked increase in ADH from 37.3 +/- 6.3 muU/min to 176.6 +/- 72.6 muU/min during the recovery hour (P smaller than 0.05). Concomitant with these changes urine osmolality decreased significantly beginning as early as the initial hour of immersion from 1044 +/- 36 to 542 +/- 66 mosmol/kg H2O during the final hour of immersion (P smaller than 0.001). Recovery was associated with a significant mean increase in Uosm of 190 +/- 40 mosmol/kg H2O over the final hour of immersion (P smaller than 0.001). The suppression of ADH occurred without concomitant changes in plasma tonicity. These studies are consistent with the suggestion that in hydrated subjects undergoing immersion suppression of ADH release contributes to the enhanced free water clearance, which has been previously documented.

Characterization of renal response to prolonged immersion in normal man

1980 ◽  
Vol 49 (2) ◽  
pp. 184-188 ◽  
Author(s):  
M. Epstein ◽  
A. G. DeNunzio ◽  
M. Ramachandran
Keyword(s):  
Weight Loss ◽  
Water Immersion ◽  
The Body ◽  
Normal Male ◽  
Immersion Period ◽  
Prolonged Duration ◽  
Normal Man ◽  
Male Subjects ◽  
Central Hypervolemia

During the initial phase of spaceflight, there is a translocation of fluid from the lower parts of the body to the central vascular compartment with a resultant natriuresis, diuresis, and weight loss. Whether this natriuresis and diuresis result in the attainment of a new steady state or whether the circulatory adjustment is incomplete is the subject of continuing controversy. Because water immersion is regarded as an appropriate model for studying the redistribution of fluid that occurs in weightlessness, we carried out an immersion study of relatively prolonged duration in order to characterize the temporal profile of the renal adaptation to central hypervolemia. Twelve normal male subjects underwent an immersion study of 8-h duration in the sodium-replete state. Immersion resulted in marked natriuresis and diuresis which were sustained throughout the immersion period. The failure of that natriuresis and diuresis of immersion to abate or cease despite marked extrcellular fluid volume contraction as evidenced by a mean weight loss of -2.2 ± 0.3 kg suggests that central blood volume was not restored to normal and that some degree of central hypervolemia probably persisted.

scholarly journals THE EFFECT OF EXERCISE ON RENAL PLASMA FLOW IN NORMAL MALE SUBJECTS

1948 ◽  
Vol 27 (5) ◽  
pp. 639-644 ◽  
Author(s):  
Carleton B. Chapman ◽  
Austin Henschel ◽  
John Minckler ◽  
Arthur Forsgren ◽  
Ancel Keys
Keyword(s):  
Plasma Flow ◽  
Renal Plasma Flow ◽  
Normal Male ◽  
Male Subjects

Characterization of the Natriuresis Caused in Normal Man by Immersion in Water

1972 ◽  
Vol 43 (2) ◽  
pp. 275-287 ◽  
Author(s):  
M. Epstein ◽  
D. C. Duncan ◽  
L. M. Fishman
Keyword(s):  
Water Immersion ◽  
Control Period ◽  
Free Water ◽  
Fractional Excretion ◽  
Normal Male ◽  
Free Water Clearance ◽  
Fractional Excretion Of Sodium ◽  
Sodium Load ◽  
Proximal Tubular ◽  
Normal Man

1. The effects of 4–6 h of water immersion on the renal excretion of water and electrolytes were studied in thirteen normal male subjects in balance on a constant diet containing 150 mEq of Na and 100 mEq of K per day. Each subject was studied during a control period, consisting of quiet sitting, and during water immersion to the neck. 2. Immersion resulted in a natriuresis beginning within the first hour, with the rate of sodium excretion eventually exceeding that of the control period by 3–4-fold; potassium excretion also increased. Despite a progressively negative water balance during the immersion studies, urine flow was greater during the first 4 h and free water clearance was greater during the first 2 h of immersion than during the control study. 3. The demonstration of a highly significant increase in fractional excretion of sodium during immersion suggests that the natriuresis of water immersion is not attributable to changes in filtered sodium load. 4. The prompt onset of the natriuresis, the concomitant kaliuresis and the fact that aldosterone secretion under the conditions of study was probably already suppressed make it unlikely that the natriuresis of water immersion is mediated solely by decreases in aldosterone activity. 5. The data suggest that the natriuresis caused by water immersion is the result of decreased fractional reabsorption of sodium proximal to the renal diluting site. The mechanism whereby increased proximal tubular sodium rejection occurs in relation to immersion remains unclear.

Effects of Angiotensin II and Aldosterone on Diastolic Function In Vivo in Normal Man

1994 ◽  
Vol 87 (4) ◽  
pp. 397-401 ◽  
Author(s):  
P. B. M. Clarkson ◽  
N. M. Wheeldon ◽  
C. MacLeod ◽  
M. Tennent ◽  
T. M. MacDonald
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Diastolic Function ◽  
Left Ventricular ◽  
Diastolic Filling ◽  
Normal Male ◽  
Normal Man ◽  
Male Subjects ◽  
Left Ventricular Diastolic Filling

1. Doppler echocardiographic indices of diastolic function and systemic haemodynamics were studied in response to infusions of angiotensin II (1, 2, 5 and 10 ng min−1 kg−1), D-aldosterone (2, 4, 10 and 20 ng min−1 kg−1) and placebo [0.9% (w/v) NaCl] in ten normal male subjects. 2. Dose-related increases in systolic and diastolic blood pressure were observed with angiotensin II infusion at rates of 2 ng min−1 kg−1 and above, whereas no changes in blood pressure occurred with D-aldosterone. No changes in aortic stroke distance or heart rate were seen with either angiotensin II or aldosterone infusion. 3. Compared with placebo, angiotensin II infusion produced a dose-related prolongation of the isovolumic relaxation time [mean and 95% confidence intervals 12.0 (8.2–15.8) ms, P < 0.001] at 10 ng min−1 kg−1, and a significant reduction in the ratio between early and late transmitral flow velocity integrals at 2 ng min−1 kg−1, [−0.84 (−1.63 to −0.05), P < 0.05] and 5 ng min−1 kg−1 [−0.76 (−1.47 to −0.05), P < 0.05]. No changes in Doppler echocardiographic indices of diastolic function were observed with D-aldosterone infusion. 4. These data suggest that angiotension II, even at a sub-pressor concentration, produces an impairment of left ventricular diastolic filling, which occurs independently of its effect on aldosterone release.

A Comparison of the Renal and Neuroendocrine Effects of Two 5-Hydroxytryptamine Renal Prodrugs in Normal Man

1993 ◽  
Vol 85 (5) ◽  
pp. 607-614 ◽  
Author(s):  
T. C. Li Kam Wa ◽  
S. Freestone ◽  
R. R. Samson ◽  
N. R. Johnson ◽  
M. R. Lee
Keyword(s):  
Renal Plasma Flow ◽  
Plasma Renin ◽  
Urinary Sodium Excretion ◽  
Serum Growth Hormone ◽  
Plasma Aldosterone Concentration ◽  
Urinary Dopamine ◽  
Normal Man ◽  
Male Subjects ◽  
Placebo Infusion ◽  
Observation Period

1. The effects of 1 h intravenous infusions of equimolar amounts (45 nmol min−1 kg−1) of two putative 5-hydroxytryptamine renal prodrugs, 5-hydroxy-L-tryptophan and γ-L-glutamyl-5-hydroxy-L-tryptophan, were investigated in a randomized, placebo-controlled, cross-over study in nine healthy male subjects. 2. Cumulative urinary 5-hydroxytryptamine excretion over the 3 h observation period rose by about 370-fold after 5-hydroxy-L-tryptophan and 390-fold after γ-L-glutamyl-5-hydroxy-L-tryptophan when compared with placebo infusion. Urinary 5-hydroxy-L-tryptophan excretion was three times higher after administration of γ-L-glutamyl-5-hydroxy-L-tryptophan than after 5-hydroxy-L-tryptophan infusion. Urinary 5-hydroxyindole-3-acetic acid excretion after 5-hydroxy-L-tryptophan infusion was significantly greater than that after γ-L-glutamyl-5-hydroxy-L-tryptophan administration. Urinary dopamine excretion was not affected by either compound when compared with placebo. 3. 5-Hydroxy-L-tryptophan significantly reduced urine flow rate and urinary sodium excretion. γ-L-Glutamyl-5-hydroxy-L-tryptophan was antinatriuretic but did not affect urine output. These changes occurred without significant alterations in effective renal plasma flow and glomerular filtration rate. 4. Both 5-hydroxy-L-tryptophan and γ-L-glutamyl-5-hydroxy-L-tryptophan significantly increased plasma aldosterone concentration without a concomitant rise in plasma renin activity. The increase after γ-L-glutamyl-5-hydroxy-L-tryptophan was smaller and delayed. 5-Hydroxy-L-tryptophan, but not γ-glutamyl-5-hydroxy-L-tryptophan, increased serum growth hormone concentration. 5. There was a significant increase in diastolic blood pressure after 5-hydroxy-L-tryptophan administration, but not after γ-L-glutamyl-5-hydroxy-L-rryptophan. 6. These results show that both prodrugs generate 5-hydroxytryptamine. The antinatriuresis after both compounds is presumably mediated by intrarenally generated 5-hydroxytryptamine and this appears to be predominantly a tubular effect. The urinary metabolite data and greater extrarenal effects produced by 5-hydroxy-L-tryptophan indicate that the glutamyl derivative is relatively more selective for the kidney than 5-hydroxy-L-tryptophan.

scholarly journals Renal hemodynamic effects differ between antidiabetic combination strategies: randomized controlled clinical trial comparing empagliflozin/linagliptin with metformin/insulin glargine

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Christian Ott ◽  
Susanne Jung ◽  
Manuel Korn ◽  
Dennis Kannenkeril ◽  
Agnes Bosch ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Insulin Glargine ◽  
Vascular Resistance ◽  
Renal Plasma Flow ◽  
Renal Perfusion ◽  
Renal Hemodynamics ◽  
Controlled Clinical Trial ◽  
Combination Therapies ◽  
Combination Strategies

Abstract Background Type 2 diabetes causes cardio-renal complications and is treated with different combination therapies. The renal hemodynamics profile of such combination therapies has not been evaluated in detail. Methods Patients (N = 97) with type 2 diabetes were randomized to receive either empagliflozin and linagliptin (E+L group) or metformin and insulin glargine (M+I group) for 3 months. Renal hemodynamics were assessed with para-aminohippuric acid and inulin for renal plasma flow (RPF) and glomerular filtration rate (GFR). Intraglomerular hemodynamics were calculated according the Gomez´ model. Results Treatment with E+L reduced GFR (p = 0.003), but RPF remained unchanged (p = 0.536). In contrast, M+I not only reduced GFR (p = 0.001), but also resulted in a significant reduction of RPF (p < 0.001). Renal vascular resistance (RVR) decreased with E+L treatment (p = 0.001) but increased with M+I treatment (p = 0.001). The changes in RPF and RVR were different between the two groups (both padjust < 0.001). Analysis of intraglomerular hemodynamics revealed that E+L did not change resistance of afferent arteriole (RA) (p = 0.116), but diminished resistance of efferent arterioles (RE) (p = 0.001). In M+I group RA was increased (p = 0.006) and RE remained unchanged (p = 0.538). The effects on RA (padjust < 0.05) and on RE (padjust < 0.05) differed between the groups. Conclusions In patients with type 2 diabetes and preserved renal function treatment with M+I resulted in reduction of renal perfusion and increase in vascular resistance, in contrast to treatment with E+I that preserved renal perfusion and reduced vascular resistance. Moreover, different underlying effects on the resistance vessels have been estimated according to the Gomez model, with M+I increasing RA and E+L predominantly decreasing RE, which is in contrast to the proposed sodium-glucose cotransporter 2 inhibitor effects. Trial registration: The study was registered at www.clinicaltrials.gov (NCT02752113) on April 26, 2016

24-h profile of serum rT3 and serum 3,3'-T2 in normal man

1980 ◽  
Vol 94 (4) ◽  
pp. 503-506 ◽  
Author(s):  
Jørgen Weeke ◽  
Peter Laurberg
Keyword(s):  
Diurnal Variation ◽  
Normal Male ◽  
Serum Samples ◽  
Serum Free ◽  
Short Intervals ◽  
Normal Man ◽  
Night And Day ◽  
Male Subjects ◽  
Serum Tsh

Abstract. In a previous study we found a night surge in serum free T3 varying in parallel with that of serum TSH. In order to evaluate whether diurnal alterations in peripheral iodothyronine monodeiodination may be involved we have measured two products of peripheral deiodination, 3,3',5'-T3 (rT3) and 3,3'-T2 in serum samples obtained at short intervals during a 24-h period in 5 normal male subjects. Serum rT3 was rather stable during the period albeit with a trend towards lower levels during the night when the subjects were in bed. In order to obtain a measure of free rT3 a free rT3 index was calculated using the combined variations in per cent free T4 and free T3. Night and day levels of this rT3 index were found identical, suggesting a lack of diurnal variation in serum free rT3. Likewise serum 3,3'-T2 levels were identical during the day and night periods. The results suggest that variations in peripheral iodothyronine deiodinations are not involved in the night increase in serum free T3.

Thermoregulatory responses to cold water at different times of day

1999 ◽  
Vol 87 (1) ◽  
pp. 243-246 ◽  
Author(s):  
John W. Castellani ◽  
Andrew J. Young ◽  
James E. Kain ◽  
Michael N. Sawka
Keyword(s):  
Cold Water ◽  
Water Immersion ◽  
Early Morning ◽  
Cold Water Immersion ◽  
Time Of Day ◽  
Mean Skin Temperature ◽  
Mean Body Temperature ◽  
Metabolic Heat ◽  
Body Temperature Change ◽  
The Mean

This study examined how time of day affects thermoregulation during cold-water immersion (CWI). It was hypothesized that the shivering and vasoconstrictor responses to CWI would differ at 0700 vs. 1500 because of lower initial core temperatures (Tcore) at 0700. Nine men were immersed (20°C, 2 h) at 0700 and 1500 on 2 days. No differences ( P > 0.05) between times were observed for metabolic heat production (M˙, 150 W ⋅ m−2), heat flow (250 W ⋅ m−2), mean skin temperature (T sk, 21°C), and the mean body temperature-change in M˙(ΔM˙) relationship. Rectal temperature (Tre) was higher ( P < 0.05) before (Δ = 0.4°C) and throughout CWI during 1500. The change in Tre was greater ( P < 0.05) at 1500 (−1.4°C) vs. 0700 (−1.2°C), likely because of the higher Tre-T skgradient (0.3°C) at 1500. These data indicate that shivering and vasoconstriction are not affected by time of day. These observations raise the possibility that CWI may increase the risk of hypothermia in the early morning because of a lower initial Tcore.

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