Volume-activated K+ and Cl- pathways of dissociated epithelial cells (MDCK): role of Ca2+.

Osmotic swelling of dissociated Madin-Darby canine kidney (MDCK) cells in NaCl medium is followed by shrinking (regulatory volume decrease, or RVD) or in KCl medium by secondary swelling. The cation ionophore gramicidin has little effect on volumes of isotonic cells but accelerates volume-activated changes in either medium. Immediately after hypotonic exposure, the membrane becomes transiently hyperpolarized followed by depolarization.

Net efflux of chloride from cell suspensions measured with a K+ electrode.

Under appropriate conditions (presence of cation ionophores) net KCl efflux measured with a K+ electrode can be used to estimate conductive Cl- fluxes, a sensitive procedure that allows continuous recording. The procedure was tested in human red cells by demonstrating effects of ionophores and of an anion transport inhibitor, and in dissociated MDCK cells by demonstration of cAMP and volume-activated Cl- fluxes.

Dissolution of bile duct stones.

Mono-octanoin can be used either alone or as an adjunct to other techniques to dissolve cholesterol bile duct stones. This solvent can be administered through an existing T tube, through the nasobiliary route, or percutaneously through the liver. Unlike basket extraction, which requires a mature T-tube sinus tract, mono-octanoin can be used immediately postoperatively or for home dissolution therapy.

Small-bowel obstruction caused by heterotopic pancreas in an adult.

Aberrant pancreatic tissue has been found in several abdominal and intrathoracic locations, most frequently in the stomach or duodenum. Heterotopic pancreas in the jejunum or ileum is a rare, usually asymptomatic, incidental finding. A review of the English language literature since 1950 shows only one pediatric and one adult case of heterotopic pancreas causing small bowel intussusception.

Activation of K+ and Cl- channels by Ca2+ and cyclic AMP in dissociated kidney epithelial (MDCK) cells.

In dissociated MDCK cells, activators of the cyclic AMP system cause depolarization detectable by changes in fluorescence of the membrane potential sensitive dye bisoxonol. Addition of forskolin (60 microM), vasopressin (2 microM), 8-bromo-cyclic AMP (0.5 mM) or 1-epinephrine (10 microM) depolarized the cells substantially in low Cl- (5 mM) but had little effect in high Cl- (140 mM) solution.

Enhancement of conductive anion permeability in cultured cells by cetiedil.

Cetiedil, a drug that is reported to block K+-channels, substantially increases the conductive C1- permeability of Chinese hamster ovary (CHO) cells. The permeability was monitored by volume changes in cells treated with gramicidin to increase the cation permeability. Under this circumstance, increases in Cl- conductances result in volume changes detectable by electronic sizing, with the direction determined by the gradients of the permeating ions.

Regulation of amino acid uptake by phorbol esters and hypertonic solutions in rat thymocytes.

Growth factors, mitogens, and malignant transformation can alter the rate of amino acid uptake in mammalian cells. It has been suggested that the effects of these stimuli on proliferation are mediated by activation of Na+/H+ exchange. In lymphocytes, Na+/H+ exchange can also be activated by phorbol esters and by hypertonic media.

Voltage-dependent increase in ionized cytoplasmic calcium in the L6H9 muscle cell line detected with quin2.

The concentration of free Ca2+ ions in the cytoplasm ([Ca2+]i) is a key parameter in the function of muscle cells. This study describes the effect of membrane depolarization on [Ca2+]i in differentiating cells of the L6H9 line of rat skeletal muscle. [Ca2+]i was assessed using the fluorescent indicator quin2.

Osmotic activation of the Na+/H+ antiport in protein kinase C-depleted lymphocytes.

The Na+/H+ antiport of rat thymic lymphocytes is activated when protein kinase C is stimulated by phorbol esters. A similar activation of the antiport is obtained when the cells are treated with hypertonic solutions. We tested the possibility that protein kinase C also mediates the osmotic activation of Na+/H+ exchange.

Bromo-A23187: a nonfluorescent calcium ionophore for use with fluorescent probes.

4-Bromo-A23187, a halogenated analog of the widely studied divalent cation ionophore A23187, is a nonfluorescent Ca2+ ionophore suitable for use in the calibration of cytoplasmic free Ca2+ by fluorescent probes. Br-A23187 is shown to saturate Ca2+ sites in quin-2-loaded rat thymic lymphocytes in a manner essentially identical to ionomycin.

Cation and anion transport pathways in volume regulatory response of human lymphocytes to hyposmotic media.

The regulatory volume decrease of osmotically swollen human peripheral blood lymphocytes can be inhibited by agents acting on volume-activated K+- or Cl--transport pathways. Quinine, cetiedil, and 3,3'-dipropylthiadicarbocyanine were found to block the volume-induced K+ transport by interaction with sites on the outside face of the membrane, perhaps by competition with external K+. Drugs known to influence calmodulin action inhibit both volume-induced K+ and Cl- transport to varying degrees.

Stimulation of hexose uptake in rat thymic lymphocytes by phorbol ester. A role for Ca2+ and Na+/H+ exchange?

The tumor promoter 12-0-tetradecanoyl phorbol-13-acetate (TPA) stimulates hexose uptake into rat thymocytes. This study explores two possible messengers of this stimulation: changes in cytosolic [Ca2+], and activation of the Na+/H+ antiport. The cytosolic level of Ca2+, determined by the fluorescence of quin-2, was elevated by TPA, and this rise required extracellular Ca2+.

Labelling of the human erythrocyte glucose transporter with 3H-labelled cytochalasin B occurs via protein photoactivation.

Irradiation of human erythrocyte membranes with 3H-labelled cytochalasin B results in specific photolabelling of the glucose transporter. The action spectrum of photolabelling has a maximum at approx. 280 nm, whereas the absorption spectrum of cytochalasin B is maximal at 210 nm.

Ionic events during the volume response of human peripheral blood lymphocytes to hypotonic media. II. Volume- and time-dependent activation and inactivation of ion transport pathways.

Hypotonic dilution of human peripheral blood lymphocytes (PBL) induces large conductive permeabilities for K+ and Cl-, associated with the capacity of the cells to regulate their volumes. When rapid cation leakage is assured by the addition of the ionophore gramicidin, the behavior of the anion conductance pathway can be independently examined. Using this technique it is demonstrated that the volume-induced activation of Cl- transport is triggered at a threshold of approximately 1.

Ionic events during the volume response of human peripheral blood lymphocytes to hypotonic media. I. Distinctions between volume-activated Cl- and K+ conductance pathways.

Human peripheral blood lymphocytes (PBL), when placed into hypotonic media, first swell and then shrink back to their original volumes because of a rapid KCl leakage via volume-activated K+ and anion permeation pathways. By using gramicidin, a cation channel-forming ionophore, cation transport through the cell membrane can be shunted so that the salt fluxes and thus the volume changes are limited by the rate of the net anion movements. The "gramicidin method," supplemented with direct measurements of volume-induced ion fluxes, can be used to assess the effects of drugs and of various treatments on cation and anion permeabilities.

Allotransplantation of human parathyroid tissue without immunosuppression.

Organ culture facilitates successful transplantation of endocrine tissue in allogenic and xenogenic rodent systems. The major obstacle in applying this approach to human tissue is the difficulty in keeping adult human tissue alive in organ culture for a prolonged period. For this reason we have used an in vivo culture system that allows preservation of endocrine tissue for weeks or months.

Incidental coenurosis: larval cestode presenting as an axillary mass.

This article describes the occurrence of a coenurus, the encysted larval stage of a cestode of the genus Multiceps, within the axilla of a 40-year-old Nigerian woman. The patient had a history of intraductal carcinoma of the breast two years prior to the finding of an ipsilateral axillary mass. Pathologic evaluation of the biopsy specimen yielded the diagnosis of coenurosis.

Glucagonomas. Ultrastructure and immunocytochemistry.

Pancreatic tumors harboring glucagon immunoreactive cells were found in four patients with diabetes mellitus. Alpha-cell (glucagon) granules were present in three tumors; pancreatic polypeptide (PP) immunoreactive cells were detected in two. In two patients the tumors were malignant and one of these had the glucagonoma syndrome; the other was a member of a family with MEN-type I syndrome.

Resection of gastrinoma in the Zollinger-Ellison syndrome.

Patients with the Zollinger-Ellison syndrome have been managed by total gastrectomy and more recently, by the use of H2-receptor antagonists. An alternative approach has been to identify those who might be cured by excision of a pancreatic islet-cell tumor without removal of the stomach. The course of such a patient is reported.

Purification of liver cytosolic proteins that stimulate triacylglycerol synthesis.

Heat-stable rat liver cytosolic proteins that stimulate triacylglycerol synthesis catalyzed by adipose tissue or liver microsomal enzymes have been isolated in a highly purified state. Their molecular weight ranges were found to be 35 000 - 45 000, 20 000 - 28 000, and 8000 - 12 000. The protein with molecular weight 20 000 - 28 000 and pI 7.