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PubMed1965

LOCALIZATION OF ERYTHROCYTE MEMBRANE SULFHYDRYL GROUPS ESSENTIAL FOR GLUCOSE TRANSPORT.

The reactions of three organic mercurial compounds, chlormerodrin, parachloromercuribenzoate (PCMB), and parachloromercuribenzenesulfonate (PCMBS) with intact red blood cells, hemolyzed red cells, hemoglobin solutions, and hemoglobin-free ghosts have been characterized. Both PCMB and PCMBS react with only 2 to 3 sulfhydryl groups per mole of hemoglobin in solution, whereas chlormerodrin reacts with 6 to 7. In hemoglobin-free ghosts, however, all three reagents react with a similar number of sulfhydryl groups, approximately 4 x 10(-17) moles per cell, or about 25 per cent of the total stromal sulfhydryl groups, which react with inorganic mercuric chloride. In the intact cell the membrane imposes a diffusion barrier; chlormerodrin and PCMB penetrate slowly, whereas PCMBS does not. Kinetic studies of chlormerodrin binding to intact cells reveal that the majority of stromal sulfhydryl groups is located inside the diffusion barrier, with only 1 to 1.5 per cent (or 1 to 1,400,000 sites per cell) located outside of this barrier. Reaction of PCMBS with intact cells is limited to this small fraction on the outer membrane surface. All three reagents are capable of inhibiting glucose transport in the red cell. With chlormerodrin and PCMBS it was demonstrated that the inhibition results from interactions with the sulfhydryl groups located on the outer surface of the membrane.

Biological Transport↗
PubMed1964

THE ROLE OF RADIOISOTOPE RENAL SCANNING IN THE ASSESSMENT OF RENAL DISEASE.

Experience with 500 radio-chlormerodrin renal scans has shown that the technique can detect (1) altered renal function, both focal and generalized, (2) space-occupying kidney lesions, and (3) renal size and disease in some cases in which the blood urea nitrogen is elevated and the excretory urogram inconclusive.The technique is valuable as an adjunct to the intravenous pyelogram since it may discriminate more disease than was thought to be present or may distinguish between anomalous variations in renal outline and calyceal displacement from parenchymal disease. The technique is completely harmless and there are no known contraindications to the test agent, radio-chlormerodrin.

Angiography↗
PubMed1990

Mercury compounds: lipophilicity and toxic effects on isolated myocardial tissue.

Lipophilicity is suggested to modulate the diffusion and the cytotoxic effects of mercury compounds. To investigate this, the positive inotropic effect of four Hg compounds (HgCl2, CH3HgCl, chlormerodrin, bromomercurihydroxypropane) was studied in catecholamine-depleted isolated heart muscle preparations. The rate of development of the positive effect was inversely correlated to the concentration in the case of HgCl2 and chlormerodrin, i.e. the product of concentration (c) and time to half-maximal effect (t50) remained constant. This was in accordance with the assumption of a permeation-controlled rate of action, as was shown earlier for p-chloromercuriphenyl-sulfonic acid. In addition, the c X t50 values of the individual mercurials decreased hyperbolically with the increase in lipophilicity as measured by the octanol/water partition. The results support the view that the toxicity of mercurials increases with their lipid solubility. In conjunction with the previously reported negative inotropic effect of Hg compounds, a model is proposed allocating thiol groups responsible for the negative inotropic action to lipid compartments within the cell membrane, while SH groups conveying the increase in contraction force are thought to be situated at the internal surface of the sarcolemma.

Animals↗
PubMed1977

Determination of extraction fraction by a double-tracer method.

A relatively simple dual-tracer method for measuring renal extraction fraction was compared with the direct method. In the dual-tracer method an extracted and nonextracted tracer are mixed together and administered into the arterial circuit and samples of venous blood are obtained. The ratio of recovered to injected tracer then determines the extraction fraction. In the direct method tracer is administered directly into the renal artery and the total venous effluent is collected. Extraction fraction is then calculated as arteriovenous difference divided by the quantity injected. In our experiments the extraction for 201Tl and 203Hg-chlormerodrin were determined. The extraction fraction for 201Tl averaged 81 +/- 5% by the direct method and 81 +/- 6% by the dual-tracer technique (r = 0.94). The extraction fraction for 203Hg-chlormerodrin was found to change as a function of the renal blood flow. At normal flow the extraction fraction averaged 48% by the direct method and 45% by the dual-tracer technique. At reduced flow, in contrast, it averaged 78% by the direct method and 71% by the dual-tracer technique.

Animals↗
PubMed1976

Triple isotope scintiphotography for differentiating between renal cysts and renal tumors.

As a routine diagnostic approach to patients who present hematuria or abnormal findings in X-ray films such as intravenous pyelograms, the cases are submitted to serial scintiphotography every two minutes after the intravenous administration of 250 muCi of 131I-Hippuran and to renography with PHO/GAMMA Scintillation Camera (Nuclear-Chicago). When scintiphotography with 131I-Hippuran reveals filling defect in the kidney region, scintiphotography with 150 muCi of 203Hg-chlormerodrin and renal blood flow scintiphotography after antecubital intravenous injection of 10 mCi of 99mTc are carried out. The present report concerns 8 cases of renal tumor and 5 cases of renal cyst confirmed by X-ray examination and surgical operation. The scintiphotography revealed decreased uptake of 131I-Hippuran and 203Hg-chlormerodrin in both tumor and cyst sites, exhibiting round or band-shaped filling defects. On the other hand, renal blood flow scintiphotography with 99mTc demonstrated the cyst as a filling defect but failed to visualize most of tumors. Accordingly, these techniques are available for differential diagnosis of the two lesions.

Adult↗
PubMed1977

Renal tubular handling of drugs.

The renal excretion of drugs is a vectorial quantity, the resultant of physiologic mechanisms that have directional orientation and magnitude. Magnitude is limited by a variety of extrarenal factors including plasma protein binding and the volume of the total body water. The contributions of the glomeruli and tubules to excretion varies with age. This fact has clinical relevance, especially in newborn children and older patients. Although protein binding reduces the amount of a drug that can be filtered, it usually does not alter the rate of proximal tubular secretion of charged organic molecules. Reabsorption of the filtered fluid from tubular lumens creates concentration gradients favoring the reabsorption of drugs, but the movement of drug molecules out of luminal fluid is hindered by the formation of polar drug metabolites in the liver. Although there are only a few examples in the literature, it is probable that many drugs are reabsorbed by a carrier-mediated process located in the proximal tubules. A major difference exists between the renal handling of chlormerodrin, a neutral mercurial, and of mersalyl, an acidic mercurial. Chlormerodrin is reabsorbed (as a complex with cysteine) by a carrier-mediated process; mersalyl is secreted by one of the organic anion transport systems.

Absorption↗
PubMed1985

Pharmacological enhancement of recovery in experimental hydronephrosis.

The effects of mannitol, methylprednisolone, furosemide, inosine, indomethacin and captopril on the recovery from hydronephrosis were examined in rat kidneys. After 1 week of ureteral obstruction, left ureterocystostomy was performed in order to release the obstruction. Following ureteral release, mannitol, methylprednisolone, inosine, furosemide, captopril and indomethacin were given intravenously or orally. A saline group and non-treated control rats were also examined for comparison. 4 weeks after ureterocystostomy, 0.5 microCi of 203Hg-labelled chlormerodrin was given intravenously and the animals were sacrificed 48 h later. The left kidneys were significantly heavier in the mannitol-, methylprednisolone-, and inosine-treated groups than those of the control groups. The chlormerodrin uptake ratios of the left kidneys were significantly higher in the mannitol-, methylprednisolone-, captopril- and indomethacin-treated groups than in the control groups. These results suggest that the release of obstruction solely is not complete treatment for hydronephrosis, but that appropriate medical treatment may enhance the recovery from hydronephrosis.

Animals↗
PubMed1975

Effect of diuretics on oxidative phosphorylation of dog kidney mitochondria.

An effect of diuretics on cellular metabolism has been shown. In order to examine further the direct effect of diuretics on renal mitochondria, their effect on isolated cortical (C) and outer medullary (OM) mitochondrial respiration was examined. Oxygen consumption rate (QO2) was measured in a Gilson oxygraph utilizing either glutamate-malate or succinate as substrate. QO2, expressed in nanoatoms of O2 per milligram of protein per minute, was always higher in C than OM: 140.7 +/- 2.8 VS. 121.2 +/- 2.4 (P less than 0.001) with glutamate-malate and 181.1 +/- 6.3 vs. 129.7 +/- 5.2 (P less than 0.001) with succinate. A dose-response curve was constructed for each of the following: sodium ethacrynate, furosemide, chlorothiazide, acetazolamide and chlormerodrin. All diuretics inhibited C and OM equally. The 50% inhibitory molar concentration for EA was 6.2 times 10(-4); for furosemide 1.5 times 10(-3); for chlorothiazide 8.1 times 10(-3); for acetazolamide 10.8 times 10(-3); and for chlomerodrin 3.1 times 10(-5). Neither cysteine nor dithiothreitol inhibited the effect of EA. The effect of chlormerodrin was abolished by cysteine. These results demonstrate that while a difference exists between C and OM mitochondria during control studies, each of the diuretics examined exerted an equal inhibitory effect on mitochondrial respiration from both C and OM. Mercurials are the most potent inhibitors and presumably exert their effect by reacting with sulfhydryl groups. They are followed in potency by ethacrynic acid, furosemide, chlorothiazide and acetazolamide.

Animals↗
PubMed1993

Estimate of the number of urea transport sites in erythrocyte ghosts using a hydrophobic mercurial.

In this paper a variety of mercurials, including a pCMB-nitroxide analogue, were used to study urea transport in human red cell ghosts. It was determined that the rate of inhibition for pCMBS, pCMB, pCMB-nitroxide, and chlormerodrin extended over four orders of magnitude consistent with their measured oil/water partition coefficients. From these results, we concluded that a significant hydrophobic barrier limits access to the urea inhibition site, suggesting that the urea site is buried in the bilayer or in a hydrophobic region of the transporter. In contrast, the rate of water inhibition by the mercurials ranged by only a factor of four and did not correlate with their hydrophobicities. Thus, the water inhibition site may be more directly accessible via the aqueous phase. Under conditions that leave water transport unaffected, we determined that < or = 32,000 labeled sites per cell corresponded to complete inhibition of urea transport. This rules out major transmembrane proteins such as band 3, the glucose carrier, and CHIP28 as candidates for the urea transporter. In contrast, this result is consistent with the Kidd (Jk) antigen being the urea transporter with an estimated 14,000 copies per cell. From the experimental number of urea sites, a turnover number between 2-6 x 10(6) sec-1 at 22 degrees C is calculated suggesting a channel mechanism.

4-Chloromercuribenzenesulfonate↗
PubMed1989

The action of organic mercury compounds on the function of isolated mammalian heart muscle.

The effects of four organic mercury compounds (methylmercuric chloride; bromomercurihydroypropane, BMHP; chlormerodrin; p-chloromercuribenzoic acid, PCMB) on mechanical and electrical functions of guinea-pig papillary muscles were investigated. An initial decline in contraction force was followed by a transient positive inotropic response. The first was accompanied by a shortening of the action-potential duration and by a reduction of the depolarization velocity and the duration of the Ca2+-dependent slow response. The latter was characterized by an indirect component (release of noradrenaline) and by a direct component, which was dependent on the stimulation rate and on the extracellular concentration of Na+ and K+. The direct positive effect, therefore, was likely to have resulted from inhibition of the sarcolemmal Na+ + K+-ATPase. This notion was confirmed by experiments with isolated membrane particles. The prevalence of the negative or positive inotropic action of these compounds could be ascribed to their lipophilic or hydrophilic properties, respectively.

Action Potentials↗