Citation Information: J Clin Invest. 1978;62(1):182-190. https://doi.org/10.1172/JCI109104.
Abstract
The method of producing experimental glucagon deficiency by administration of glucagon antiserum was evaluated in rats. A pool of antisera was prepared, the affinity of which exceeded that of the glucagon receptors of liver cell membranes, whereas the binding capacity of the volume used amounted to more than one-third of the total glucagon content in the rat pancreas. That rapid, extensive, and lasting neutralization of glucagon had taken place after antiserum treatment was indicated by the following findings: When examined more than 1 h after the injection and after 60 min of exercise-stimulated glucagon production, all rats had excess free antibodies in plasma. The concentration of free glucagon was lowered to one-third of the concentration in control rats; at 37°C plasma samples could bind 25% of additional 300 pmol/liter of glucagon in 10 s, and 69% in 120 s; the glycemic response to exogenous glucagon was abolished. Antiserum treatment, however, had no effect on blood glucose in rats fasted for 3 and 10 h, in chemically sympathectomized and adrenomedullectomized rats, and in 48-h-fasted, acutely adrenalectomized rats. The antiserum was found to contain 460 nmol/liter of antibody-bound glucagon, originating in the rabbit in which the antiserum was raised. However, antibody preparations from which the bound glucagon had been effectively removed were equally ineffective in lowering the basal blood glucose in rats, although in three-fourths of the rats the concentration of free glucagon was lowered beyond detection limit.
Authors
J. J. Holst, H. Galbo, E. A. Richter
Citation Information: J Clin Invest. 1978;62(1):20-28. https://doi.org/10.1172/JCI109107.
Abstract
To delineate the potential role of disordered glucose and glucose-precursor kinetics in the abnormal carbohydrate metabolism of chronic renal failure, alanine and glucose production and utilization and gluconeogenesis from alanine were studied in patients with chronic compensated renal insufficiency and in normal volunteers. With simultaneous primed injection-continuous infusions of radiolabeled alanine and glucose, rates of metabolite turnover and precursor-product interrelationships were calculated from the plateau portion of the appropriate specific activity curves. All subjects were studied in the postabsorption state. In 13 patients with chronic renal failure (creatinine = 10.7±1.2 mg/100 ml; mean±SEM), glucose turnover was found to be 1,035±99.3 μmol/min. This rate was increased 56% (P = 0.003) over that observed in control subjects (664±33.5 μmol/min). Alanine turnover was 474±96.0 μmol/min in azotemic patients. This rate was 191% greater (P = 0.007) than the rate determined in control subjects (163±19.4 μmol/min). Gluconeogenesis from alanine and the percent of glucose production contributed by gluconeogenesis from alanine were increased in patients with chronic renal failure (192% and 169%, respectively) as compared to controls (P < 0.05 for each). Alanine utilization for gluconeogenesis was increased from 40.2±3.86 μmol/min in control subjects to 143±39.0 μmol/min in azotemic patients (P < 0.05). The percent of alanine utilization accounted for by gluconeogenesis was not altered in chronic renal insufficiency. In nondiabetic azotemic subjects, mean fasting glucose and immunoreactive insulin levels were increased 24.3% (P = 0.005) and 130% (P = 0.046), respectively.
Authors
Sheldon Rubenfeld, Alan J. Garber
Citation Information: J Clin Invest. 1978;62(1):214-220. https://doi.org/10.1172/JCI109109.
Abstract
The effect of the sulfone compound 4,4′-diaminodiphenyl sulfone (dapsone) on normal human polymorphonuclear leukocytes (PMNL) has been investigated in vitro. The drug has a dramatically beneficial effect in dermatitis herpetiformis in which the PMNL and immune complexes has been stressed to be of importance for the development of the skin lesions. Pruritus disappears and the inflammatory eruptions clear within a few days of starting therapy. The effect of dapsone has been evaluated on the different stages of phagocytosis. Using dapsone concentrations (1-30 μg/ml) comparable with those found after therapeutic doses, we have found that the drug interferes primarily with the myeloperoxidase (MPO)-H2O2-halide-mediated cytotoxic system in the PMNL. No effect was observed on random locomotion, chemotaxis, phagocytic ingestion, oxidative metabolism, or the release of lysosomal enzymes. Kinetic studies in a cell-free system with purified MPO revealed a competitive type of inhibition using varying concentrations of NaI. Furthermore, the inhibition resulted in reduced candidicidal activity during phagocytosis of Candida albicans, and reduced cytotoxicity to adjacent mammalian cells measured as the 51Cr release from virus-induced lymphoma cells. Because the MPO-H2O2-halide system not only fulfills the antimicrobial activity but is suggested to be a modulator of the inflammatory reaction as well, the action of dapsone in dermatitis herpetiformis may in part be explained by its effect on this system.
Authors
O. Stendahl, L. Molin, C. Dahlgren
Citation Information: J Clin Invest. 1978;62(1):6-13. https://doi.org/10.1172/JCI109114.
Abstract
The renal handling of the biologically active glucagon component (the 3,500-mol wt fraction of immunoreactive glucagon [IRG]) and the contribution of the kidney to its overall peripheral metabolism were studied in normal and uremic rats. The metabolic clearance rate of glucagon was 31.8 ± 1.2 ml/min per kg in normal animals and was diminished by approximately one-third in each of three groups of rats with compromized renal function: 22.3±1.6 ml/min per kg in partially (70%) nephrectomized; 22.9±3.3 ml/min per kg in bilaterally ureteral ligated; and 23.2±1.2 ml/min per kg in bilaterally nephrectomized animals. In normal rats the kidney contributed 30% to the overall metabolic clearance of the hormone and the renal extraction of endogenous and exogenous glucagon was similar, averaging 22.9±1.6% and was independent of plasma IRG levels over a wide range of arterial concentrations. The remnant kidney of partially (70%) nephrectomized animals continued to extract substantial amounts (16.6±4.2%) of the hormone, but accounted for only 8% of the total peripheral catabolism of IRG. In the two groups of animals with filtering kidneys, renal glucagon uptake was linearly related to its filtered load and could be accounted for by glomerular filtration and tubular reabsorption. However, the kidneys of animals with both ureters ligated (renal extraction of inulin = 3.2±1.8%) and hence virtual absence of glomerular filtration, continued to extract 11.5±1.9% of the renal arterial glucagon, contributing by 9% to its overall metabolic clearance, indicating that IRG uptake occurs also from the post glomerular capillaries.
Authors
D. S. Emmanouel, J. B. Jaspan, A. H. Rubenstein, A. H-J. Huen, E. Fink, A. I. Katz
Citation Information: J Clin Invest. 1978;61(6):1421-1427. https://doi.org/10.1172/JCI109061.
Abstract
We previously reported that rabbit renal cortical collecting tubules can secrete bicarbonate in vitro (i.e., there can be net transport from bath to lumen, causing the concentration in the lumen to increase). Net bicarbonate secretion was observed most often when rabbits had been pretreated with NaHCO3 and were excreting alkaline urine before being killed for experiments. The purpose of the present studies was to elucidate the mechanism involved by testing the effects of ion substitutions and drugs on collecting tubules that were secreting bicarbonate. Acetazolamide inhibited net bicarbonate secretion, suggesting that the process is dependent upon carbonic anhydrase. Net bicarbonate secretion also decreased when sodium in the perfusate and bath was replaced by choline, but not when chloride was replaced by nitrate or methylsulfate. Ouabain had no significant effect. Amiloride caused net bicarbonate secretion to increase. The rate of net secretion did not correlate with transepithelial voltage. The results are compared to those in turtle urinary bladders that also secrete bicarbonate. There are no direct contradictions between the results in the two tissues, i.e., in turtle bladders acetazolamide also inhibited bicarbonate secretion and ouabain had no effect. Nevertheless, it seems unlikely that net secretion of bicarbonate by collecting tubules involves specific exchange for chloride, as has been proposed for turtle bladders, because replacement of chloride by other anions did not inhibit bicarbonate secretion by collecting tubules. It was previously shown that the collecting tubules in vitro also may absorb bicarbonate, especially when the rabbits have been treated with NH4Cl and are excreting acid urine before being killed. The effects of drugs on net bicarbonate secretion found in the present studies are compared to their previously reported effects on net bicarbonate absorption and the possibility is discussed that bicarbonate absorption and secretion are independent processes, as was previously proposed for turtle bladders.
Authors
Thurman D. McKinney, Maurice B. Burg
Citation Information: J Clin Invest. 1978;61(6):1448-1455. https://doi.org/10.1172/JCI109064.
Abstract
Neurological abnormalities are a major cause of morbidity in patients with renal failure. The pathophysiology of these neurological changes is unclear, and the effects on them of dialysis and return of renal function have not been well studied. Studies were done in 31 patients who had acute renal failure (ARF), all of whom were either treated with dialysis within 5 days or did not survive. Studies on these patients included the electroencephalogram (EEG), motor nerve conduction velocity, and plasma Ca++ and parathyroid hormone (PTH) levels. Studies were done at the time ARF was diagnosed, after stabilization on dialysis, during the diuretic phase of ARF, and 3 mo after recovery from ARF. In 16 patients with acute or chronic renal failure who did not survive and in nine patients without renal disease who died, measurements were made in brain of content of Na+, K+, Cl−, Ca++, Mg++, and water.
Authors
Jerry D. Cooper, Virginia C. Lazarowitz, Allen I. Arieff
Citation Information: J Clin Invest. 1978;61(6):1463-1470. https://doi.org/10.1172/JCI109066.
Abstract
Measurements of respiratory mechanics, arterial blood gases, and pulmonary vascular resistance were made before and 15 min after inhalation challenge with Ascaris suum extract in dogs with natural sensitivity to this antigen. 25 of 47 dogs were treated before inhalation challenge with a prostaglandin inhibitor (90 mg/kg of aspirin or 2 mg/kg of indomethacin by intravenous infusion). In response to the challenge, bronchospasm developed in approximately half (responders) of each group reflected by decreases in mean specific respiratory system conductance and arterial oxygen tension. While the dogs were breathing room air, pulmonary vascular resistance remained unchanged after antigen challenge in the responders not given aspirin or indomethacin, but increased significantly and was associated with a lesser degree of arterial hypoxemia in the responders pretreated with either of the prostaglandin inhibitors. Prevention of arterial hypoxemia by oxygen breathing blocked an increase in pulmonary vascular resistance in four pretreated responders. No changes in respiratory mechanics, pulmonary hemodynamics, or arterial blood gases were noted in the 21 dogs who did not develop bronchospasm regardless of whether or not they were pretreated. 12 additional dogs in whom arterial hypoxemia was produced by 10% oxygen breathing, showed an increase in pulmonary vascular resistance that was not potentiated by pretreatment with aspirin in 6. We conclude that in acute experimental canine asthma, vasodilator prostaglandins appear to blunt the hypoxic pulmonary vasoconstrictor response, thereby further compromising gas exchange but preventing the development of pulmonary hypertension.
Authors
Martin A. Cohn, Horst Baier, Adam Wanner
Citation Information: J Clin Invest. 1978;61(6):1488-1497. https://doi.org/10.1172/JCI109069.
Abstract
The effects of endogenous and exogenous hyperglucagonemia on the specific binding of glucagon to hepatocyte receptors was studied, as was the response of cAMP to glucagon. In streptozotocin diabetic rats, blood glucose and plasma glucagon increased and plasma insulin decreased as compared with controls. Insulin treatment in diabetic rats restored blood glucose and plasma glucagon toward normal and elevated plasma insulin. Specific binding of 125I-glucagon to isolated hepatocytes (106 cells) decreased in diabetic rats (8.17±0.38%) compared to controls (14.05±0.87%) and was restored by insulin treatment (12.25±0.93%). Specific binding of 125I-insulin in controls was 7.30±10.16%; it increased in diabetic rats to 12.50±0.86%, and decreased in diabetic rats after insulin treatment (9.08±0.87%). Scatchard analysis and the competition plots of the data indicate that decreased glucagon binding and increased insulin binding in diabetes were due to change in the number of receptors rather than a change in their affinity. Hepatocyte cAMP response to glucagon (0.25-5.0 ng/ml) was almost abolished in diabetic rats and was restored with insulin treatment.
Authors
Sam J. Bhathena, Nancy R. Voyles, Stewart Smith, Lillian Recant
Citation Information: J Clin Invest. 1978;61(6):1508-1518. https://doi.org/10.1172/JCI109071.
Abstract
An in vitro approach to the study of single nephron function in uremia has been employed in evaluating the control of fluid reabsorption by the renal superficial proximal straight tubule (PST). Isolated segments of PSTs from the remnant kidneys of uremic rabbits (stage III) were perfused in vitro and their rate of fluid reabsorption compared with normal PSTs and with PSTs derived from the remnant kidneys of nonuremic rabbits (stage II). All segments were exposed to a peritubular bathing medium of both normal and uremic rabbit serum thereby permitting a differentiation to be made between adaptations in function which are intrinsic to the tubular epithelium and those which are dependent upon a uremic milieu.
Authors
Leon G. Fine, Walter Trizna, Jacques J. Bourgoignie, Neal S. Bricker
Citation Information: J Clin Invest. 1978;61(6):1519-1527. https://doi.org/10.1172/JCI109072.
Abstract
Resistance of the chronically diseased kidney to vasopressin has been proposed as a possible explanation for the urinary concentrating defect of uremia. The present studies examined the water permeability and adenylate cyclase responsiveness of isolated cortical collecting tubules (CCT) from remnant kidneys of uremic rabbits to vasopressin. In the absence of vasopressin the CCTs of both normal and uremic rabbits were impermeable to water. At the same osmotic gradient, addition of a supramaximal concentration of vasopressin to the peritubular bathing medium led to a significantly lower net water flux per unit length (and per unit luminal surface area) in uremic CCTs than in normal CCTs. Transepithelial osmotic water permeability coefficient, Pf, was 0.0232 ±0.0043 cm/s in normal CCTs and 0.0059±0.001 cm/s in uremic CCTs (P < 0.001). The impaired vasopressin responsiveness of the uremic CCTs was observed whether normal or uremic serum was present in the bath.
Authors
Leon G. Fine, Detlef Schlondorff, Walter Trizna, Richard M. Gilbert, Neal S. Bricker
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