[Effects of dopamine and adenosine on regulation of water-electrolyte exchange in Amoeba proteus].

Dopamine and adenosine both regulate transport of sodium chloride in the renal tubules in mammals. We have studied the effect of dopamine and adenosine on spontaneous activity of contractile vacuole of Amoeba proteous. Both substances stimulated contractile vacuole. The effect of dopamine was suppressed by D2 receptor antagonist, haloperidol, but not by D1 antagonist, SCH 39166. Adenylate cyclase inhibitor, 2.5-dideoxyadenosine, suppressed the effect of dopamine, but not of adenosine. Inhibitor of protein kinase C, staurosporine, in contrast, blocked the effect of adenosine, but not dopamine. Notably, dopamine opposed effect of adenosine and vice versa. These results suggest that similar effects of dopamine and adenosine could be mediated by different intracellulare mechanisms.

[Disease from the point of view of evolution].

In the process of evolution, such compensatory reactions as enhanced reabsorption of sodium chloride and an increase of arterial pressure could be formed only for compensation of acute pathological states (blood loss, dehydration). At present they remain similarly adequate in acute disturbances of blood circulation and of water-electrolyte balance. However, in severe chronic pathology of heart and kidney they often lose their compensatory function and even become dangerous. Evolution of human and of human society has created novel social conditions of adaptation. They are of humanitarian and technogenic character by promoting prevention and treatment of diseases.

[Effect of acetylcholine and acetylcholinesterase on the activity of contractile vacuole of Amoeba proteus].

Acetylcholine (ACh, 1 microM) stimulates activity of the contractile vacuole of proteus. The effect of ACh is not mimicked by its analogs which are not hydrolyzed by acetylcholinesterase (AChE), i. e., carbacholine and 5-methylfurmethide. The effect of ACh is not sensitive to the blocking action of M-cholinolytics, atropine and mytolone, but is suppressed by N-cholinolytic, tubocurarine. The inhibitors of AChE, eserine (0.01 microM) and armine (0.1 microM), suppress the effect of ACh on amoeba contractile vacuole. ACh does not affect activation of contractile vacuole induced by arginine-vasopressin (1 microM), but it blocks such effect of opiate receptors agonist, dynorphin A1-13 (0.01 microM). This effect of ACh is also suppressed by the inhibitors of AChE. These results suggest that, in the above-described effects of ACh, AChE acts not as an antagonist, but rather as a synergist.

Involvement of endogenous digitalis-like factors in voluntary selection of alcohol by rats.

This study tested the hypothesis that endogenous digitalis-like factor (DLF) is involved in the development of alcohol dependence in rats. In 33 male Wistar rats in conditioned place preference (CPP) experiment, ethanol evoked increase in time spent in the ethanol-associated compartment (702+/-82 in ethanol-treated vs. 426+/-86 sec in the controls). Digoxin pretreatment (125 microg/kg, i/p) did not affect the time spent in the water-associated compartment (476+/-80 sec), but prevented the acquisition of ethanol CPP (385+/-112 sec in ethanol-paired side, P<0.05). In a two bottle choice test, where rats (n=6 per group) chose between drinking water and 9% ethanol, immunization against two putative DLFs, marinobufagenin and ouabain (MBG and OLC) resulted in a 60% increase of ethanol consumption. Acute intragastric administration of 9% ethanol to the rats was associated with increased OLC in cerebrospinal fluid, and stimulated urinary excretion of MBG and OLC. Thus, in rats, digoxin, which mimics the effects of DLFs, suppresses the free choice of alcohol, while immunization against DLFs is associated with alcohol seeking behavior.

[A cytophotometric analysis of the activity of oxidative enzymes and Na, K-ATPASE in vertebrate nephrons at different levels of sodium transport in the kidney]. / Tsitofotometricheskii analiz aktivnosti okislitel'nykh fermentov i Na, K-ATFazy v nefrone pozvonochnykh zhivotnykh pri raznykh urovniakh transporta natriia v pochke

Using quantitative cytochemistry, activities of Na, K-ATPase, succinate dehydrogenase (SDH) and alpha-keto-glutarate dehydrogenase (alpha-KDH) was investigated in cells of renal tubules at different levels of sodium reabsorption in the kidney. The activity of these enzymes in mammals and birds renal tubule cells was found to be higher than in the cells of corresponding renal tubules of cold-blooded vertebrates. This corresponds to the increased total amount of reabsorbed sodium in the kidney of warm-blooded animals. The summer frogs, as compared to the winter ones, exhibit higher activities of SDH and Na,K-ATPase in the proximal tubule cells where changes in sodium reabsorption are also noted. In the kidney of marine teleosts, a negative correlation between U/PNa and the activity of SDH and Na,K-ATPase in the cells of proximal and distal tubule was observed. Aldosterone was found to stimulate sodium reabsorption and to activate Na,K-ATPase.SDH and alpha-KDH mainly in the distal convoluted tubule. Furosemide was observed to inhibit sodium reabsorption and to reduce SDH and Na,K-ATPase activities in cells of the proximal tubule and Henle's loop. In the kidney of adrenalectomized rats, both sodium reabsorption and activities of Na,K-ATPase, SDH, alpha-KDH decreased in all the segments of the nephron. The data obtained suggest that changes in sodium reabsorption may be coupled with those in the activities of the investigated enzymes.

[Acetylcholinesterase and the ADH-dependent transport of water in the amphibian bladder]. / Atsetilkholinésteraza i ADG-zavisimyi transport vody v mochevom puzyre amfibii.

It was found that acetylcholine (ACh) at the concentration of 10(-3) M inhibited ADH-stimulated water transport through the wall of amphibian urinary bladder. This effect was suggested to be caused by an interaction of ACh with acetylcholinesterase (AChE) rather than by a stimulation of the M- or N-cholinoreceptor. The inhibitory action of ACh was completely suppressed in the presence of various AChE inhibitors (physostigmine, proserine, armine, Gd-42, acridine-iodmethylate), while an inhibitor of butyrylcholinesterase (BuChE), AD-4, failed to affect it. In accord with this observation the activity of AChE (but not of BuChE) was demonstrated in the urinary bladder epithelium. Since, in addition to the hydrosmotic effects of pituitrine, 8-arginine-vasopressin or oxytocin, ACh blocked also effects of forskolin or cyclic AMP, one may conclude that it acts at some post-cyclic AMP production stage. AChE-dependent inhibition of the ADH-stimulated water transport decreased significantly when the serosal pH was raising from 7.2 to 8.0, but was augmented by serosal acidification (pH 6.8), whereas such pH alterations did not affect the activity of the epithelium AChE. The effect of ACh under consideration was suppressed by adding amiloride (10(-4) M) to the serosal solution. Similarly, the ACh effect was blocked by an inhibitor of Ca-dependent K+ channels, 4-aminopyrdine, which in addition prevented the inhibition of the ADH-stimulated water transport by the serosal acidification. It was noteworthy that some other K+ channel blockers (Ba2+, Cs+, tetraethylammonium, apamine, quinine) did not affect either the water transport or the antipituitrine effect of ACh. In conclusion, we suggest that the inhibitory action of ACh on the ADH-stimulated water transport in the urinary bladder is mediated through the intracellular acidification resulting from ACh interaction with AChE. It is unlikely that the acidification is merely a consequence of the ACh hydrolysis, rather the ACh-AChE interaction induces directly an increase in the proton conductivity of the basolateral membrane of the urinary bladder epithelium.

[Spontaneous and induced permeability of the tight junctions in the bladder epithelium of the frog Rana temporaria]. / Spontannaia i indutsirovannaia pronitsaemost' plotnykh kontaktov épiteliia mochevogo puzyria liagushki Rana temporaria.

The spontaneous and induced alterations in paracellular permeability of the isolated frog urinary bladder were studied. For estimation of the tight junction (TJ) permeability, a fluorescent dye uranine was used. No morphological or functional evidences for the TJ opening were found in the autumn-winter period, both in the control and after the osmotic flow stimulation by 25 mg/ml pituitrine (P) or serosal mannitol (200 mM). In the spring, a spontaneous uranine efflux through the bladder wall from the mucosal solution was found in parallel with an increase in the basal water flow and a decrease in the responses of the bladder to P and serosal hypertonicity. At the same time, the intercellular substance remained to be a barrier for water. In the autumn-winter the TJ opening could be induced by adding sulfhydryl reagents, p-chloromercury-phenyl-sulfonic acid (PCMPS) or N-ethylmaleimide (NEM), to the serosal solution. However, NEM was effective only when added to the mucosal solution. The uranine efflux induced by sulfhydryl reagents was accompanied with a marked hydroosmotic flow in parallel with a diminished sensitivity to P, the barrier properties of intercellular substances were lost. As evidenced by electron microscopy, PCMPS induced a gradual destruction of TJ structures, while certain cytoplasmic structures were not affected. The uranine efflux in the autumn-winter frogs could be induced by an artificial osmotic gradient after preincubation of the bladders in the isotonic solution with P. Some possible intracellular mechanisms causing both spontaneous and induced alterations in the TJ permeability are discussed.

[Effect of various antimicrotubular drugs on the osmotic water flow through the wall of frog's urinary bladder]. / O vliianii nekotorykh antimikrotubuliarnykh agentov na osmoticheskii tok vody cherez stenku mochevogo puzyria liagushki

The action of antimicrotubular drugs (colchicine, vinblastine and copper) on the osmotic water flow through the wall of the urinary bladder of Rana temporaria has been studied. The osmotic gradient was made by five- or tenfold dilution of the internal Ringer solution. The water flow was estimated gravimetrically. The water flow was induced by pituitrin (50 milliunits/ml), cyclic AMP (cAMP, 0.5-10(-3) M) and nystatine (3.5-10(-5) M). Pituitrin and cAMP and all the antimicrotubular drugs were added from the serosal surface of the bladder. Nystatine was introduced with the help of a fixed polyethylene tube. Preincubation with colchicine lasted 4 hours and that with vinblastine and copper (CuSO4), 1 hour. The drug concentrations varied between 10(-5)--10(-4) M. All the drugs studied showed a significant inhibitory effect toward pituitrin. The action of cAMP on the water flow was seen inhibited in the presence of colchicine and copper. The nystatine induced water flow was supressed by copper, colchicine being in this case inactive. A conclusion is drawn that the inhibition of cAMP formation does not cause a decreased pituitrine effect in the presence of antimicrotubular drugs. It has been assumed that the microtubules may be involved in the directed water flow within the cell.

[The role of protein kinase C and muscarinic cholinoreceptors in vasopressin-stimulated water transport]. / O roli proteinkinazy C i muskarinovykh kholinoretseptorov v stimulirovannom vazopressinom vodnom transporte.

The role of protein kinase C (PKC) in the control of vasopressin-stimulated water transport in the frog urinary bladder and its modulation by M2-agonist oxotremorine has been studied. Using the PKC inhibitor, staurosporine we showed that PKC in the region pf the basal membrane suppressed vasopressin-stimulated water transport, whereas PKC in the apical region potentiated this transport. It was also found that from the two types of oxotremorine action on stimulated water transport determined by its concentration only inhibition is mediated through PKC.

[The effect of lithium on the tissue levels of electrolytes and hyaluronic acid levels in the kidney papilla in the rat]. / Vliianie litiia na soderzhanie élektrolitov v tkaniakh i gialuronovoi kisloty v pochechnom sosochke krys.

Injections of 0.2 M LiCl i. p. (1 ml/100 g/day) induced polydipsia in rats drinking tap water. The plasma lithium concentration and its content in the erythrocytes, skeletal muscles, renal tissue were significantly higher in the rats drinking tap water as compared with rats drinking saline. No significant differences in the body volume of extracellular fluid, muscle water, Na, K content and their muscle intracellular concentrations were noted between the "lithium" and the control rats. Na content in the plasma and the renal cortex--medullar Na gradient were decreased in the "lithium" rats drinking tap water. The hyaluronic acid content in renal papilla was increased in all rats receiving lithium injections. After an injection of ADH the papillary hyaluronic acid content markedly decreased in control rats while it decreased only insignificantly in "lithium" rats. The impairment of the ability of urine concentrating and polyuria in "lithium" rats seems to be partly connected with an enhancement of the polymerization degree of renal papillar hyaluronic acid.

[Effect of oxidative metabolism inhibitors on ADH-dependent transport of water in the bladder of Rana temporaria]. / Vliianie ingibitorov okislitel'nogo metabolizma na ADG-zavisimyi transport vody v mochevom puzyre liagushki Rana temporaria.

It has been demonstrated that inhibitors of oxidative metabolism--rotenone, amytal, antimycin A, oligomycin and 2,4-dinitrophenol--block hydroosmotic response of the urinary bladder of the frog to pituitrin, cAMP and serosal hypertonicity caused by 200 mosm mannitol. Electron donors sodium ascorbate and phenasinemethasulphate completely abolish the inhibitory effect of rotenone and antimycin A (but not of oligomycin). It is concluded that intracellular reactions which are sensitive to the effect of the inhibitors of oxidative metabolism, begin from the step after cAMP formation.

[Succinate dehydrogenase and Na+-K+-ATPase activities in cells of rat kidney tubules during increased excretion of sodium, caused by furosemide]. / Aktivnost' suktsinatdegridrogenazy i Na-K-zavisimoi ATF-azy v kletkakh pochechynkh kanal' tsev krysy pri natriiureze, vyzvannom furosemidom

In the cells of nephron tubules an effect of furosemide on kidney function and on succinate dehydrogenase and Na+-K+-ATPase activities was studied cytochemically. Administration of furosemide (1 mg per 100 g of body weight) increased excretion of sodium and potassium. If the rate of filtration through Malpighian tufts was constant, the increase in Na and K excretion demonstrated the tubular effect of the diuretics. Both administration of furosemide and preincubation of the drug with kidney slices in vitro caused a decrease in succinate dehydrogenase activity in the cells of all the nephron sections. These data suggest that a direct effect of the diuretics on oxidative metabolism in renal cells took place. Alteration in the activity of Na+-K+-ATPase was observed only in vivo and in those nephron sections, where sodium reabsorption was decreased under the effect of furosemide.

[Effect of acetylcholine on the pituitrin induced osmotic flow of water through the wall of the frog urinary bladder]. / Vliianie atsetilkholina na vyzvannyi pituitrinom osmoticheskii tok vody cherez stenku mochevogo puzyria liagushki.

The role of intercellular pathways in the ADH-dependent water transport was studied on the frog urinary bladder by means of acetylcholine (AC) and other cholinergic compounds. AC (10(-3) M) was found to cause a strong suppression of the pituitrin-stimulated water flow. Analogous effect was produced by AC on the osmotic flow stimulated by cyclic adenosine monophosphate (cAMP) and theolin. The antipituitrin effect was not reproduced either by nicotine, nor by potent M-cholinomimetic agents (methylfurmetide and F-2268), and was not prevented by M- and N-cholynolytic drugs (atropine, metacin, flaxedil, hexamethonium). However, the antipituitrin effect of AC was completely removed by the anticholinesterase drugs with different mode of action (eserine, proserine, armin, acridine iodmethylate, GD-42) in concentrations of 10(-6)--10(-3) M. It was concluded that the smooth muscles contraction with the subsequent closure of the intercellular spaces was not responsible for the antipituitrinic action of AC. This effect appears to be connected with cholinesterase activation. A possible role of the phosphoinositides in the water permeability regulation of the urinary bladder wall is discussed.

[The tyrosine kinase inhibitor genistein potentiates the antidiuretic effect of vasopressin and its analogs]. / Ingibitor tirozinkinazy genistein usilivaet antidiureticheskii éffekt vazopressina i ego analogov.

Genistein was shown to potentiate the effects of all the activators of the water flow except the cAMP action. The thyrosine kinase (TK) seems to suppress the hydrosmotic action of arginine vasopressin at the period preceding the cAMP formation and to potentiate this effect afterwards.

[The mechanisms of the effect of furosemide on the water permeability of the frog bladder and on oxytocin-stimulated contractions of the rat uterus]. / Mekhanizmy vliianiia furosemida na vodnuiu pronitsaemost' mochevogo puzyria liagushki i stimulirovannye oksitotsinom sokrashcheniia matki krysy.

Furosemide increased the hydrosmotic water flow in the frog urinary bladder and promoted the ADH-like effect of inhibitors of phosphodiesterase cAMP, potentiated hydrosmotic effects of theophylline and serosal osmotic hypertonicity but failed to change the effect of pituitrin. Fur reversibly suppressed oxytocin-induced contractions in the rat myometrium, inhibited the activity of the frog urinary bladder PDE cAMP, whereas the activity of the enzyme from the rat medulla and myometrium was activated by saluretic. Incubation of the myometrium strips in Fur resulted in a decrease in the cAMP content of the tissue. The cAMP seems to play an important role both in the myometrium smooth muscle relaxation and in the oxytocin-activated contractions.