Yu. V. Natochin

Evolutionary Physiology: History, Principles

1) The history of comparative and evolutionary physiology since the early XIX century is given; 2) The methods of evolutionary physiology are described; 3) Principles of the evolution of function are discussed at every level of physiological organization (cellular, functional units of the organ, the organ itself, functional systems) as they apply to the kidney and to the regulation of salt and water balance; and 4) General questions of evolutionary physiology covering physico-chemical factors in evolution of functions, the development of the integrity of an organism, the origin of physiological adaptation, the development of interconnection of physiological systems are discussed.

Osmolality and electrolyte concentration of hemolymph and the problem of ion and volume regulation of cells in higher insects

Abstract 1. 1. The study was carried out on 22 species of insects from 5 orders. The osmolality of their hemolymph varied from 319 to 421 mOsm/kg H2O, concentration of Na+ 4.6 to 118 mM/l, K+ 6.3 to 73mM/l, Ca2+ 3.6 to 12.9 mM/l, Mg2+ 2.3 to 76 mM/l. The most abundant cation in the hemolymph of insects from higher orders is either K+ or Mg2+. 2. 2. In the muscles of lower and higher insects K+ is usually within 80–120 mM/kg wet wt. 3. 3. Most Ca2+ and Mg2+ in hemolymph is bound with protein and low molecular anions, concentration of free Ca2+ is 0.9-2.1mM/l Mg2+ 3.7–8.0 mM/l. 4. 4. It is concluded that, in insects, potassium hemolymph, cell volume regulation and accumulation of ions in the cell, are ensured by an increased osmolality of hemolymph due to a high percentage contribution of low molecular organic substances which are retained in the hemolymph due to the absence of filtration apparatus in the Malpighian tubules.

Features of osmotic and ionic regulations in Russian sturgeon (Acipenser güldenstädti Brandt).

The osmolality of blood serum of one group of Russian sturgeon fished out in Southern Caspian Sea was the same as their habitat, the other group of sturgeons had a serum osmolality several per cent lower than that of sea-water in this part of the Caspian Sea. Ion concentrations in blood serum in sturgens were similar in fresh water and the Caspian Sea. The feature of the Russian sturgeons kidney is intensive potassium secretion and a comparatively low level of magnesium secretion.

The participation of electrolytes in adaptation mechanisms of intertidal molluscs' cells to altered salinity

Abstract 1. 1. The water content, volume of inulin space, Na, K, Mg content and protein synthesis in the adductor of bivalve molluscs Mytilus edulis L. and in the foot muscle of the snails (Gastropoda) Littorina littorea (L.) were investigated at different environmental salinity. 2. 2. The reaction of mollusc cells to the decreasing of salinity appears to be automatic and independent of nervous or humoral influences. 3. 3. There is an effective mechanism of retaining potassium in the molluscs, the amount of this ion not decreasing even in the first steps of hypotony when there is a great loss of sodium and magnesium ions. The retaining of intracellular K in a wide range of environmental salinity changes enables the cell to maintain the transmembrane gradient K i K o independent of other ions by varying the cell volume. 4. 4. The stabilization of cell volume is achieved by passive influx of Na and apparently Cl into the cell at high salinities and by active removal of these ions at hypotony. 5. 5. The data acquired by means of inhibitors suggest that there exists an independent transport of Na linked to the accompanying anion (Cl, apparently) in the mollusc cells in addition to Na/K-ion exchanging mechanism, providing osmo- and volume regulation of the cell. 6. 6. Concentration of intracellular Na serves as one of the signals regulating the activity of protein synthesis of the molluscs cells in water of different salinities.

The changes of ionic composition and cell volume during adaptation of molluscs (Littorina) to lowered salinity

Abstract 1. 1. The changes of water content, volume of inulin space and Na, K and Mg content in the foot muscle and hepatopancreas of gastropod molluscs Littorina littorea , L. saxatilis and L. obtusata acclimated to lowered salinity (14–16‰) were investigated. 2. 2. The molluscs have an inability to completely regulate cell volume, the hydration level of which increases sharply at the first period of hypotony and partly re-establishes itself during prolonged acclimation to dilute seawater. 3. 3. During adaptation of L. littorea to lowered salinity the role of ions (especially potassium) in the cell osmoregulation increases. There is an effective mechanism of retaining potassium in the cells of these molluscs, the ionic quantity not decreasing even in the first steps of hypotony, when there is a great loss of sodium and magnesium ions.

PROSTAGLANDIN-DEPENDENT OSMOTIC WATER PERMEABILITY OF THE FROG AND TROUT URINARY BLADDER

Washout of autacoids from serosal Ringer solution, using a repeated change of the solution of the frog and trout urinary bladder, was accompanied by a pronounced rise in the osmotic water permeability: the water transport in the frog rose from 0.05 +/- 0.02 to 1.21 +/- 0.26 microliter min-1.cm-2, in the trout, from 0.041 +/- 0.011 to 0.26 +/- 0.034 microliter min-1.cm-2. Such an increase in the osmotic water permeability in the trout and frog urinary bladder occurred in the background of a decrease in the prostaglandin E2 concentration in the serosal Ringer solution. This permeability increase was accompanied by the formation of aggregates of intramembranous particles in the apical plasma membrane of the trout and frog urinary bladder. A decrease in the osmotic water permeability was achieved by the addition to the serosal Ringer solution of 10-8 M prostaglandin. Experiments on the frog urinary bladder have shown that prostaglandins E1, I2 and F2 alpha also decrease the osmotic water permeability. Vasotocin increased the osmotic water permeability in the frog urinary bladder but did not affect the osmotic water permeability of the trout urinary bladder. The data obtained indicates a role of the endogenous prostaglandin production in maintaining the low osmotic water permeability in the frog and trout urinary bladder. A suggestion is made that in the vertebrate evolution, colonisation of the fresh-water was connected with the maintenance of the low osmotic water permeability via participation of prostaglandins, whereas the vasotocin hydroosmotic effect developed in the vertebrate evolution later and provided for the possibility of the water absorption, osmotic homeostasis and animal migration from fresh-water to the land.

Cobalt-dependent stimulation of sodium transport in the amphibian skin and nephron

One to ten millimolar CoCl2, when applied to the outer surface of the apical membrane of the frog skin (Rana temporaria), reversibly increased the potential differences and short-circuit current. These observations suggest that Co2+ may control the gating system of the sodium channel. In the kidney of the newt (Triturus vulgaris), proximal reabsorption is increased under the influence of 0.5 mM CoCl2 injected into the lumen. When CoCl2 (0.5 mM) was injected into the lumen of the distal tubule of the newt kidney, Na+ and Cl- reabsorption was stimulated simultaneously Ca2+ transport was inhibited. The data obtained suggested that Co2+ may affect the state of the sodium and calcium channels of nonexcitable membranes of amphibia, and thus may be involved in the regulation of the function of the renal tubules.

Reduced magnesium content in non-pigmented eyes of the honey bee (Apis mellifera L.)

1. 1. Electrolyte contents of the eye and haemolymph of the honey bee Apis mellifera L. were found to be identical in wild type bees and eye colour mutants except reduced Mg content in the ommochrome-deficient eyes. 2. 2. In the wild type bee eyes, the concentration of Ca and Mg peaked in the different zones. 3. 3. In the mutant snow, the peak of Mg and large amount of S were absent from the eyes, while the Ca peak showed no noticeable changes. 4. 4. Pigment granules are suggested to be capable of sequestering Ca, Mg and S and this property as to Mg and S is strongly correlated with the presence of ommochromes in these organelles.

Electrolyte composition of embryo and larva of the Russian sturgeon in the process of development

Abstract 1. 1. The dry solids of eggs and larvae are gradually decreased, the most pronounced mass reduction being observed in larvae. In the process of egg development the water content is significantly increased after fertilization and the transition to larva state. 2. 2. In the first two days after fertilization a loss of a minor amount of Na + is observed, K + . Mg 2+ and Ca 2+ contents vary but slightly. 3. 3. In the course of a week of life in fresh water before passing to active feeding the larvae get from the environment and accumulate Na + , K + and Ca 2+ .

Effect of diuretics on the secretion and reabsorption of ions in the kidney of marine teleosts

Abstract 1. 1. Black sculpine with partly aglomerular kidneys from the Barents Sea and black sculpine with glomerular kidneys from the White Sea as well as scorpion fish and mullet from the Black Sea were injected intramuscularly with Lasix, Edecrin, Brinaldix and Diamox. The kidneys of the different species of these fish showed wide variations in their reactions to the injection of diuretics. 2. 2. Following injection of Lasix, Edecrin and Brinaldix, a significant increase in the Na concentration of the urine from black sculpine and mullet was observed, associated with a decrease in Mg concentration in the former and with a sharp increase in chloride concentration in the latter. 3. 3. In experiments performed on black sculpine after simultaneous injection with diuretics and sodium sulphate it was found that diuretics while inhibiting Na reabsorption do not affect sulphate secretion. 4. 4. Lasix, Edecrin and Brinaldix seem to affect primarily Na reabsorption, while the change in the urinary concentration and excretion of other ions depends on the interrelationship between the tubular transport of Na and these ions.