Mechanisms Of Ion Regulation Research Articles

Introduction to the Symposium: Cellular Mechanisms of Ion Regulation in Arthropods

Introduction to the Symposium: Cellular Mechanisms of Ion Regulation in Arthropods

Effect of prostaglandins, cyclic nucleotides, and ions on the analgesic effect of enkephalin analogs

The effect of intracellular modulators and ions on the analgetic action of the two tetrapeptide analogs, Tyr-D-Ala-Gly-Phe-NH2 and Tyr-D-Ala-Gly-Phe (NO) NH2, was studied in rat experiments. The threshold of pain reaction to electrical stimulation of the tail, evidenced by vocalization, was measured. PGE1, PGE2, PGE2 alpha, cAMP, and dibutyryl cAMP were shown to diminish the effect of the above-mentioned enkephalin analogs. In contrast to cAMP, cGMP was not active in this respect. Among the ions under study (calcium, lithium, rubidium, and cesium), cesium was shown to be the most active. It prevented the increase of the pain reaction threshold and shortened the duration of analgesia. Lithium had no antagonistic effect as regards the enkephalin-induced analgesia. Comparison of these findings with the previously obtained data on the antagonism of the substances under consideration with morphine suggests similarities in the mechanisms of modulation of the effects of opiates and opioids. At the same time the failure of lithium to antagonize the enkephalin analogs and the presence of morphine antagonism point out that the similarities in the mechanisms of ion regulation of exogenous analgetics and enkephalins cannot be regarded as complete enough.

Influence of ouabain on Na + and K + concentration in haemolymph of Drosophila hydei and appearance of Malpighian tubules

After injection of ouabain into the body cavity, the Malpighian tubules of Drosophila larvae show a characteristic appearance which differs from the normal. The primary urine, which is mainly found in particles, is diluted and the concretions are washed away through the proximal part of the tubule and the ureter into the hindgut. In the haemolymph the Na + and K + concentrations change significantly. The K + concentration increases rapidly to double the normal, while later the Na + concentration rises up to 2·3 times the normal. Water movements are not the cause of the concentration changes because the quotient Na K varies widely. Thus primary ion regulation mechanisms are influenced in the insect body by application of g-strophanthin. This is evidence for the existence of a ouabain-sensitive ATPase, which is decisively involved in the ion transport mechanisms in the insect body.

NUTRITION AND METABOLISM OF MARINE BACTERIA. XII. ION ACTIVATION OF ADENOSINE TRIPHOSPHATASE IN MEMBRANES OF MARINE BACTERIAL CELLS.

Drapeau, Gabriel R., (Macdonald College of McGill University, Quebec, Canada) and Robert A. MacLeod. Nutrition and metabolism of marine bacteria. XII. Ion activation of adenosine triphosphatase in membranes of marine bacterial cells. J. Bacteriol. 85:1413-1419. 1963.-Isolated membranes of two species of marine bacteria, a Pseudomonas and a Cytophaga, have been shown to possess adenosine triphosphatase activity. The optimal pH for enzyme action of both organisms was 8.8. The enzyme system was found to be capable of splitting inorganic o-phosphate from adenosine triphosphate (ATP), adenosine diphosphate, adenosine monophosphate, and inosine triphosphate but not from inorganic pyrophosphate. Mg(++) was required for enzyme activity; with the Pseudomonas species, the optimal Mg(++) to ATP ratio was 1:1. Ca(++) could not replace Mg(++). In the presence of the optimal concentration of Mg(++), the enzyme system was further stimulated, nonspecifically, by a number of different salts. Maximal activation was achieved at an ionic strength of 0.3 to 0.4. No evidence of an adenosine triphosphatase specifically activated by a combination of Na(+) and K(+) was obtained with either organism. No effect of ouabain on either the membrane adenosine triphosphatase activity or Na(+) transport by whole cells could be detected. The results suggest that the mechanism of ion regulation in marine bacterial cells is different from that in animal cells.

The effects of the ionic environment on the chromatin structures of bacteria.

The aggregation of bacterial chromatin into compact masses under a variety of circumstances (exposure to high salt concentrations, low temperature, ultraviolet irradiation, metabolic inhibitors, and starvation) is a function of the concentration of electrolytes in the environment of the cell. This effect can be prevented or reversed in an environment deficient in salts. The observations indicate that chromatin aggregation is a consequence of interaction of cations (Na+ and K+, in particular) and polymerized desoxyribose nucleic acid, which behaves as an anionic gel. The organisms used (Shigella dysenteriae, Escherichia coli, Bacillus cereus, Caryophanon latum, a wild yeast, and a Geotrichum sp.) were able to maintain their "normal" configuration of chromatin in salt-deficient media and in media with up to 3% salt as long as their metabolism was intact. Disruption of metabolism by exposure to cold or metabolic inhibitors produced aggregation or dispersion of chromatin according to the ionic environment. This range of change in nuclear form can be produced in the living cell without apparent or permanent damage to viability. These studies indicate that bacterial and fungal cells share with cells of higher organisms the ability to regulate the influx and efflux of cations. Chromatin serves as a sensitive indicator of the integrity of these ion regulatory mechanisms. Some implications of these observations are discussed.