R. G. Luke

Effects of chloride and extracellular fluid volume on bicarbonate reabsorption along the nephron in metabolic alkalosis in the rat. Reassessment of the classical hypothesis of the pathogenesis of metabolic alkalosis.

Volume expansion has been considered essential for the correction of chloride-depletion metabolic alkalosis (CDA). To examine the predictions of this hypothesis, rats dialyzed against 0.15 M NaHCO3 to produce CDA and controls, CON, dialyzed against Ringer-HCO3 were infused with either 6% albumin (VE) or 80 mM non-sodium chloride salts (CC) added to 5% dextrose (DX) and studied by micropuncture. CDA was maintained in rats infused with DX. VE expanded plasma volume (25%), maintained glomerular filtration rate (GFR), but did not correct CDA despite increased fractional delivery of total CO2 (tCO2) out of the proximal tubule (36 +/- 2%) as compared with VE/CON (24 +/- 4%; P less than 0.05). In contrast, CC corrected CDA despite volume contraction (-16%) and lower GFR than CC/CON; proximal tCO2 delivery in CC/CDA (29 +/- 4%) did not differ from VE/CDA. CC was associated with an increment in tCO2 excretion. The data strongly suggest that maintenance and correction of CDA are primarily dependent upon total body chloride and its influences on intrarenal mechanisms and not on the demands of sodium or fluid homeostasis.

HEPARIN TREATMENT FOR POST-PARTUM RENAL FAILURE WITH MICROANGIOPATHIC HÆMOLYTIC ANÆMIA

Abstract Acute renal failure and a microangiopathic haemolytic anaemia developed in a 25-year-old woman 2 weeks after a normal pregnancy. Renal biopsy showed deposition of fibrin within the lumen and the vessel walls of the renal arterioles. The case is similar to others with a syndrome thought to be irreversible; significant improvement in renal function followed heparin therapy in this patient. It is suggested that the syndrome may be due to a renal vasospastic reaction to oxytocic drugs together with the enhanced coagulation mechanisms of the early puerperium.

NORMAL SERUM-LIPIDS IN RENAL-TRANSPLANT PATIENTS

In contrast to previous reports, most patients (78%) with a successful renal transplant being followed up at the University of Kentucky Medical Center had a normal serum-lipid profile. The patients with hyperlipidaema (22%) had normal fasting insulin levels; they received similar immunosuppressive therapy but were significantly older and more obese than those with normal lipids. This lower prevalence of hyperlipidaemia and the absence of fasting hyperinsulinaemia are tentatively attributed to the use of alternate-day corticosteroid therapy in stable renal-transplant patients. If confirmed, the relative infrequency of hyperlipidaemia in patients of alternate-day corticosteroid therapy would be an additional advantage of that therapy over a daily regimen.

Segmental chloride and fluid handling during correction of chloride-depletion alkalosis without volume expansion in the rat.

To determine whether chloride-depletion metabolic alkalosis (CDA) can be corrected by provision of chloride without volume expansion or intranephronal redistribution of fluid reabsorption, CDA was produced in Sprague-Dawley rats by peritoneal dialysis against 0.15 M NaHCO3; controls (CON) were dialyzed against Ringers bicarbonate. Animals were infused with isotonic solutions containing the same Cl and total CO2 (tCO2) concentrations as in postdialysis plasma at rates shown to be associated with slight but stable volume contraction. During the subsequent 6 h, serum Cl and tCO2 concentrations remained stable and normal in CON and corrected towards normal in CDA; urinary chloride excretion was less and bicarbonate excretion greater than those in CON during this period. Micropuncture and microinjection studies were performed in the 3rd h after dialysis. Plasma volumes determined by 125I-albumin were not different. Inulin clearance and fractional chloride excretion were lower (P less than 0.05) in CDA. Superficial nephron glomerular filtration rate determined from distal puncture sites was lower (P less than 0.02) in CDA (27.9 +/- 2.3 nl/min) compared with that in CON (37.9 +/- 2.6). Fractional fluid and chloride reabsorption in the proximal convoluted tubule and within the loop segment did not differ. Fractional chloride delivery to the early distal convolution did not differ but that out of this segment was less (P less than 0.01) in group CDA. Urinary recovery of 36Cl injected into the collecting duct segment was lower (P less than 0.01) in CDA (CON 74 +/- 3; CDA 34 +/- 4%). These data show that CDA can be corrected by the provision of chloride without volume expansion or alterations in the intranephronal distribution of fluid reabsorption. Enhanced chloride reabsorption in the collecting duct segment, and possibly in the distal convoluted tubule, contributes importantly to this correction.

EFFECT ON CYTOTOXICITY ANTIBODIES IN POTENTIAL TRANSPLANT RECIPIENTS OF LEUCOCYTE-POOR BLOOD- TRANSFUSIONS

In a controlled clinical trail, 40 uraemic patients received only leucocyte-poor blood (L.P.B.) while 30 uraemic controls received whole blood and ordinary packed red blood-cells (R.B.C.). Alloimmunisation by HL-A antibodies was found in 15% of the study group and 52% of the control group. Thus, L.P.B. was significantly less likely to produce alloimmunisation than ordinary whole blood or R.B.C. transfusion. Frozen R.B.C may produce even less alloimmunisation, but the advantages of L.P.B. include lower cost, prolonged storage, and ready availability in emergencies.