Effect of hypothermia on renal sodium reabsorption

Summary The relationship between sodium reabsorption and oxygen consumption was studied in an isolated rabbit kidney preparation perfused with blood at 37, 28 and 19° C. When the temperature was lowered from 37° C to 28° C and to 19°C the rate of oxygen consumption and of the maximal P.A.H. excretion (Tm P.A.H.) decreased more than that of sodium reabsorption.TheQ ₁₀ for sodium reabsorption is about 1.8, while that for maximal P.A.H. excretion is 2.5. Some hypothesis on the possible mechanisms of the lowQ ₁₀ of the Na⁺ reabsorption are forwarded.Preliminary reports have been published [Boll. Soc. Ital. Biol. Sper.43, 1019–1023 (1966) and44, 1784–1787 (1967);45, 860–862 (1969) and45, 863–865 (1969)].     

Micropuncture studies on the filtration rate of single superficial and juxtamedullary glomeruli in the rat kidney

Summary Single nephron filtration rates of superficial and juxtamedullary nephrons were determined in high and low sodium rats. Single nephron GFR was calculated from TF/P inulin and tubular flow rate in superficial nephrons and single juxtamedullary GFR from corresponding data in long loops of Henle. In low sodium rats superficial nephron GFR was 23.5±6.4 (SD)×10^–6 ml/min×g KW, juxtamedullary nephron GFR was 58.2±13.6 and total kidney GFR (C _In) was 0.94±0.16 ml/min×g KW. Using these single nephron values, total kidney GFR and a total number of 30,000 glomeruli per kidney, the number of superficial and juxtamedullary glomeruli was calculated to be 23,267 and 6,733, respectively. During high sodium diet superficial nephron GFR increased to 38.1±11.3 and single juxtamedullary GFR decreased to 16.5±6.6, total kidney GFR increasing to 1.01±0.24. Calculation again revealed the same distribution of the two nephron types. End-proximal TF/P inulin in superficial nephrons was 2.36±0.36 in low sodium and 2.31±0.28 in high sodium rats. Loops of Henle TF/P inulin and intratubular flow rate were inversely related: the highest TF/P inulin values and lowest intratubular flow rates were found in the descending limb. These data quantify the distribution of superficial and juxtamedullary nephrons on a functional basis and suggest a mechanism by which the kidney adjusts sodium excretion by altering the contribution of each nephron type to total kidney GFR.Supported by the Deutsche Forschungsgemeinschaft and the U.S. Department of the Army, through its European Research Office.     

A micropuncture study of the effect of isoprenaline on renal tubular fluid and electrolyte transport in the rat

Summary To explain the mechanism of the isoprenaline induced antidiuresis the effect of this substance on fluid and electrolyte reabsorption in various nephron segments of the rat kidney has been studied using micropuncture techniques. Isoprenaline (1.5×10^–9 mol/kg·min i.v.) decreased GFR of superficial nephrons and increased fractional proximal fluid, sodium and potassium reabsorption. However, the fractions of filtered fluid and electrolytes, which had been reabsorbed up to the early distal tubule were unchanged after isoprenaline. This indicates that the increased fractional proximal reabsorption has been completely compensated by decreased reabsorption from Henle's loops. In the distal convoluted tubules an increase in the fractional fluid and sodium reabsorption could be established using a recollection technique. Given directly into the distal tubular lumen isoprenaline stimulated the isotonic fluid reabsorption, which was measured by the Gertz split oil droplet method.From these results it is concluded that the decrease in superficial GFR and the increased distal tubular fluid and sodium reabsorption lead to the decrease in urine volume and in urinary electrolyte excretion after isoprenaline.with the technical assistance of U. Greven and S. HildebrandSupported by Deutsche ForschungsgemeinschaftPortions of this work were presented at the Meeting of the Deutsche Pharmakologische Gesellschaft in Graz, 1974 (Greven, 1974b)     

Energy source for transepithelial sodium transport in rat renal proximal tubules

Summary The effects of various metabolic inhibitors on isotonic fluid absorption (J _V ) in rat proximal tubules and on the Na⁺–K⁺-ATPase of isolated cell membranes of rat kidney cortex were investigated by the shrinking split oil droplet technique and biochemical methods respectively.Both Oligomycin (5×10^–5 M, 10^–4 M) and Antimycin A (10^–5 M, 10^–4 M) inhibited isotonic fluid absorption by 80% when applied intratubularly but only in conjunction with bovine serum albumin. At these concentrations they inhibited a Na⁺–K⁺ activated adenosine triphosphate phosphohydrolase (Na⁺–K⁺ ATPase E.C. 3.6.1.3.) of cell membranes isolated from rat kidney cortex by 77%, 82% and 55%, 95%, respectively.Sodium phosphoenolpyruvate (PEP) 5×10^–3 M could partially reverse the inhibition of the isotonic fluid absorption but only with 10^–5 M Antimycin A when the Na⁺–K⁺ ATPase inhibition was apparently small.The uncoupler, carbonyl cyanide m-chlorophenyl hydrazone (CCCP) (10^–3 M), as well as sodium cyanide (5×10^–3 M) inhibitedJ _V 100%, but only when applied through peritubular blood capillary perfusion.From these findings it was concluded thatall proximal tubular isotonic fluid absorption is supported by energy fromoxidative processes, and that in a least 80% of this sodium reabsorption, ATP from oxidative phosphorylation is directly involved, while, for the remaining 20% non ATP energy is responsible.C. J. Martin Fellow of the National Health and Medical Research Council of Australia.     

Patch-clamp study of cultured human sweat duct cells: amiloride-blockable Na+ channel

The reabsorptive duct of the eccrine sweat gland has a large transepithelial conductance consisting mainly of a high conductance to Cl^– and a smaller, amiloride-blockable Na⁺ conductance (Bijman and Frömter 1986; Quinton 1985). Cells have been cultured from sweat ducts and their properties previously studied in Ussing chambers (Pedersen 1988) and with microelectrodes (Jones et al. 1988). We have now studied the ion channels present in excised, inside-out patches of human cultured sweat duct cells, and find a marked predominance of linear, 16 pS, amiloride-blockable, low selectivity, Na⁺ channels. Such channels were seen in 54/92 (59%) of the patches, with up to 7 channels recorded in a single patch.Other channel types were seen at much lower densities. The prevalence of an amiloride-blockable Na⁺ channel in cultured duct cells clearly distinguishes these cells from cultured sweat gland secretory cells, which lack such a channel.     

自体脂肪移植配合rh EGF降低重吸收率的临床研究

目的研究自体脂肪移植配合重组人表皮生长因子(rhEGF)降低重吸收率的价值。方法选择我院2016年5月至2017年12月收治的44例各类组织缺陷患者,随机分为两组各22例。研究组采用自体脂肪移植配合rhEGF,对照组仅采用自体脂肪移植,对比两组的治疗效果。结果治疗后3个月、6个月、9个月及12个月,研究组的体表凹陷测量结果优于对照组(P<0.05)。研究组的重吸收率、重复操作次数、医疗费用及住院时间均低于对照组(P<0.05)。研究组的修复优良率为90.91%,高于对照组的63.64%(P<0.05)。研究组的满意度为95.45%,高于对照组的72.73%(P<0.05)。结论自体脂肪移植配合rhEGF应用于组织缺陷中效果明显,能有效降低重吸收率,缩短治疗时间,减轻家庭经济负担,提高患者的修复效果及满意度。     

Nierenfunktion bei Ratten mit experimentellem DOCA-Hochdruck

Summary Rats were made chronically hypertensive by unilateral nephrectomy, repeated injections of desoxycorticosterone-acetate and offering saline as drinking fluid (DOCA-rats). Unilaterally nephrectomized animals (Nephrex-rats) were used for control. Compensatory renal hypertrophy was greater in DOCA-rats than in Nephrex-rats. Diameter and length of the proximal convolute in the DOCA-group increased more than in Nephrex-rats. GFR per unit kidney weight in the DOCA-group remained unchanged as compared to untreated Wistar-rats but increased significantly in Nephrex-animals. the water and sodium load of each nephron had doubled in both groups. Nevertheless, there were no substantial changes in the fractional water and sodium reabsorption in the different segments of the nephron of DOCA-rats as compared to normal animals. In Nephrex-rats fractional sodium and water reabsorption were increased in the proximal tubule and diminished in the loop of Henle and in the distal tubule. In Nephrex-rats an indirect correlation was found between blood pressure and both water reabsorption and the transit time of Lissamine green in superficial loops of Henle but no such correlation could be found in the DOCA-group. Determination of the specific reabsorption capacity of the proximal tubules during free-flow or using the split-drop technique yielded identical values in all animals studied.

Auszugsweise vorgetragen auf der 36. Tagung (Herbsttagung) der Deutschen Physiologischen Gesellschaft in Mainz.