Some quantitative characteristics of the frog retinal rod outer segments]

Retinal rod outer segments in frogs were studied by means of light microscopy, refractometry, microspectrophotometry, and electron microscopy. Analysis of the data obtained shows that an unidentified substance, which makes up about 50% of outer segment dry weight, is lost during routine biochemical investigations. The protein parts of the rhodopsin molecules make up 85% of the outer segments proteins and 25% of outer segment dry weight. Rhodopsin molecules can be arranged in a square array with a unit cell side of about 7 nm on one side of each disk membrane. Lipids in a single membrane occupy only 2 nm, and disk membranes are strongly hydrated.     

Effects of PKC isozyme inhibitors on constrictor responses in the feline pulmonary vascular bed

The effects of G?-6976, a Ca(2+)-dependent protein kinase C (PKC) isozyme inhibitor, and rottlerin, a PKC-delta isozyme/calmodulin (CaM)-dependent kinase III inhibitor, on responses to vasopressor agents were investigated in the feline pulmonary vascular bed. Injections of angiotensin II, norepinephrine (NE), serotonin, BAY K 8644, and U-46619 into the lobar arterial constant blood flow perfusion circuit caused increases in pressure. G?-6976 reduced responses to angiotensin II; however, it did not alter responses to serotonin, NE, or U-46619, whereas G?-6976 enhanced BAY K 8644 responses. Rottlerin reduced responses to angiotensin II and NE, did not alter responses to serotonin or U-46619, and enhanced responses to BAY K 8644. Immunohistochemistry of feline pulmonary arterial smooth muscle cells demonstrated localization of PKC-alpha and -delta isozymes in response to phorbol 12-myristate 13-acetate and angiotensin II. Localization of PKC-alpha and -delta isozymes decreased with administration of G?-6976 and rottlerin, respectively. These data suggest that activation of Ca(2+)-dependent PKC isozymes and Ca(2+)-independent PKC-delta isozyme/CaM-dependent kinase III mediate angiotensin II responses. These data further suggest that Ca(2+)-independent PKC-delta isozyme/CaM-dependent kinase III mediate responses to NE. A rottlerin- or G?-6976-sensitive mechanism is not involved in mediating responses to serotonin and U-46619, but these PKC isozyme inhibitors enhanced BAY K 8644 responses in the feline pulmonary vascular bed.     

The characteristics of the microflora isolated in bovine endometritis]

117 pure bacterial cultures of numerous species isolated by the authors at acute postnatal pyo-catarrhal cattle endometritis have been studied for their virulence and resistance to 18 antibiotics with the aim to determine their etiologic role in the development of the given pathology and to make a prediction estimation of possible therapeutic and preventive efficiency of the antibiotics. The experiments on white mice have revealed pathogenic properties and virulence in most studied strains of bacteria of different species. The studied microflora is, mainly, resistant practically to all 18 tested antibiotics. A direct dependence is established between virulence of the microflora, isolated in case of endometritis, and its resistance to antibiotics.     

Reproduction of the anaphylactic reaction of isolated human smooth muscle organs and the effect of several adrenotropic substances]

A comparative study was carried out of passive sensitization of the lungs, bronchi, small and large intestine by the blood sera of patients sensitive to ambrosia pollen. Passive sensitization and subsequent anaphylactic contraction were reproduced on the isolated bronchi, lungs and the ileum. Development of this reaction was less constant in the large intestine, jejunum and the appendix. The value of anaphylactic reaction of human smooth muscle displayed significant changes with the treatment of the muscles by agents selectively acting on the beta-adrenergic receptors of these organs.     

Dependence of constrictor and dilator humoral responses of arteries and veins in the small intestine on calcium ions entering vascular myocytes

Verapamyl administered to the intestine circulation in the dose evoking no shifts in the arterial and venous resistance or in the vascular capacity, decreased 2- or 3-fold both the constrictor and dilatory responses of the arterial vessels. Against the background of Verapamyl, noradrenaline and isoproterenol did not practically change either capacity or resistance in the veins. Responses of veins to angiotensin II increased 10-fold and more, whereas they were absent after administration of atropine into the intestine circulation. Constrictor and dilatory responses of veins need to a greater extent than the arteries penetration of external calcium ions to their myocytes.     

Mechanical activity of the vascular wall: the choice of optimum conditions for the study of isolated ring segments

A new method for the study of vascular helical segments is described. The method, permitting simulation of mechanical conditions in vivo, can cause substantial changes in the experiments studying regulatory reactions in isolated fragments of the vascular bed.     

Immunochemical characteristics of the peroxidases of several mouse tissues]

Enzymes catalyzing peroxidase reaction of a lysosomal fraction in bone marrow, leucocytes, spleen, thyroid gland, stomach, kidney, heart, lungs, brain and skeletal muscle of mice were investigated by immunochemical methods. A high level of peroxidase activity was discovered in leucocytes, bone marrow, spleen, heart and lung, a lower activity appeared to be characteristic of liver, thyroid gland and kidney. The peroxidase activities in brain, skeletal muscle and stomach were low. The reaction of immunoprecipitation with myeloperoxidase-specific antiserum revealed considerable antigenic distinctions between the enzymes catalysing peroxidase reaction in various tissues of mice.     

Solubilization and several properties of NAD-glucohydrolase isolated from rabbit heart]

Methods of isolation of NAD-glucohydrolase from the fraction of heart microsomes were searched for. NAD-glucohydrolase proved to pass into a soluble state under the effect of phospholipase A, triton X-100 and Na cholate. NAD-glucohydrolase was found to possess peculiar properties; it reversibly became denatured under the effect of 6M urea, but failed to become inactivated with own substrate (NAD) at pH 8.0. In case of NAD-ases isolated from other sources the reversible denaturation by means of urea as a rule correlated with the enzyme inactivation in the presence of NAD at pH 8.0.     

Influence of extracellular magnesium on the contractile and endothelium-dependent dilatory responses of feline mesenteric arteries.

To clarify the effect of extracellular magnesium on the vascular reactivity of feline isolated mesenteric arteries, the effects of slight alterations in the extracellular magnesium concentration on the contractile and endothelium-dependent dilatory responses were investigated in vitro. The contractions, induced by noradrenaline 10(-8)-10(-5) M, were not affected in the mesenteric artery at low extracellular magnesium (0.8 mM versus to the normal, 1.2 mM). High (1.6 and 2.0 mM) magnesium exerted a modest inhibitory effect on the contractile responses. This depression of the contraction was accompanied with a significant shift to the right in the EC50 value for noradrenaline. The endothelium-dependent relaxations induced by acetylcholine 10(-8)-10(-5) M, were inhibited by high (1.6 and 2.0 mM) magnesium. Lowering of the extracellular magnesium concentration to 0.8 mM, however, failed to alter the dilatory potency of acetylcholine. The depression of the dilatory responses was also accompanied with a shift to the right in the EC50 values for acetylcholine. The present results show, that contractions and endothelium-dependent relaxations of the mesenteric artery are modulated by the extracellular magnesium asymmetrically: slight magnesium deficiency does not affect these responses, whereas elevation of the concentration of this ion inhibits both processes. Extracellular magnesium probably affects rather the binding of these contractile and endothelium-dependent dilatory agonists to their receptors than the calcium influx into the endothelial- and smooth muscle cells in this vessel.     

The effect of different doses of gonadotropins on the quantitative, morphological and cytogenetic characteristics of oocytes from CBA mice]

The effect of gonadotropins (PMSG/HCG) dose on number, quality and cytogenetic characteristics of CBA mouse oocytes was investigated. The oocytes from natural cycle were used as a control. Using of 5 IU dose led to increasing of oocytes number with no differences in their parameters from control ones. Percentage of oocytes of bed quality, with nuclear material degeneration, and parthenogenetically activated oocytes were found to increase under 10 IU and 15 IU dosage.     

The calcium-mobilizing effect of inositol-1,4,5-triphosphate in rod outer segments and disks]

The effect of inositol-1,4,5-trisphosphate (IP3) on the release of calcium ions from retinal rod discs was studied. It was shown that the release of Ca2+ from discs is an electroneutral process. The intradiscal calcium concentration during the release of the ion from the organelle decreases by 1 mM. It was found that the IP3-dependent release of Ca2+ ions from discs is activated by guanosine triphosphate and beta gamma-transducin. The increase in calcium concentration in the medium also activates the IP3-dependent release of Ca2+ ions from discs, which probably is due to the stimulation of phospholipase C. It is suggested that the functional role of the release of ions in related not to phototransduction but to slow regulatory and adaptation processes in the photoreceptor cell.     

The effect of the micromanipulations used for transgenosis on mouse development]

Non-specific effects of micromanipulation techniques used for producing transgenic mice on processes of embryonic development were studied. Zygotes obtained from C57BL and BALBxDD mice were treated as follows: (1) incubated in culture medium; (2) the male pronucleus punctured with a glass microneedle; (3) microinjected with a buffer solution; and (4) DNA (mouse P-35 oncogene with human insulin gene promoter) injected into the male pronucleus. Then zygotes were transferred into oviducts of syngeneic or allogeneic pseudopregnant females. Such treatment resulted in the intrauterine death of embryos, as well as in birth of the dead or non-viable offspring with numerous defects of development. Zygote pronucleus puncturing is the most damaging manipulation, since its effect exceeds that of the zygote incubation and is comparable with the effect of buffer of DNA injections.     

Analysis of purine- and pyrimidine-induced vascular responses in the isolated rat cerebral arteriole

Effects of extraluminal UTP were studied and compared with vascular responses to ATP and its analogs in rat cerebral-penetrating arterioles. UTP, UDP, 2-methylthio-ATP, and alpha,beta-methylene-ATP dilated arterioles at the lowest concentration and constricted them at high concentrations. Low concentrations of ATP dilated the vessels; high concentrations caused a biphasic response, with transient constriction followed by dilation. Endothelial impairment inhibited ATP- and UTP-mediated dilation and potentiated constriction to UTP but not to ATP. ATP- and 2-methylthio-ATP- but not UTP-mediated constrictions were inhibited by desensitization with 10(-6) M alpha,beta-methylene-ATP or 3 x 10(-6) M pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS). PPADS at 10(-4) M abolished the UTP-mediated constriction and induced vasodilation in a dose-dependent manner but did not affect the dilation to ATP. These results suggest that in rat cerebral microvessels 1) ATP and 2-methylthio-ATP induce transient constriction via smooth muscle P(2X1) receptors in the cerebral arteriole, 2) UTP stimulates two different classes of P(2Y) receptors, resulting in constriction (smooth muscle P(2Y4)) and dilation (possibly endothelial P(2Y2)), and 3) ATP and UTP produce dilation by stimulation of a single receptor (P(2Y2)).     

Involvement of P2X and P2U receptors in the constrictor effect of ATP on the pancreatic vascular bed

The effects of ATP on the pancreatic vascular bed were studied on the isolated rat pancreas perfused at a constant pressure so as any change in the vascular tone induces a modification in the flow rate. This study was performed in two different experimental conditions: 1) In the presence of indomethacin, inhibiting the cyclo-oxygenase and prostacyclin (PGI2) synthesis, ATP (which acts on vasodilatator P2Y receptors and vasoconstrictor P2X and P2U receptors) was used at a concentration (165 microM) which did not modify per se the vascular flow rate. With indomethacin, ATP induced a slight but significant and long lasting decrease in the flow rate. This effect is different from that induced by the stimulation of P2X receptors; it is comparable to that induced by the activation of P2U receptors. 2) In the presence of 2,2'pyridylisatogen tosilate (PIT) used at two different concentrations, the first (5 microM) inhibiting the P2Y effects on insulin secreting B cells and pancreatic vessels, the second (25 microM) inhibiting the P2X effects on pancreatic vessels. The effects of ATP are different according to the concentration of PIT. In both cases, ATP induced only a vasoconstriction. However, the kinetics of the flow rate is totally different: in the presence of 5 microM PIT, an immediate and drastic vasoconstriction was observed, followed by a long lasting vasoconstriction of lesser magnitude, which can be ascribed to P2X and P2U receptor activation, respectively. This hypothesis was confirmed by the results in the presence of PIT at 25 microM. At this concentration this compound completely suppressed the drastic and transient vasoconstriction, so that only a progressive and long lasting vasoconstriction of the P2U type could be observed. From these results, it can be concluded that: 1) PGI2 plays a part in the vasodilatator effects of ATP. 2) At the concentrations used, PIT does not block the vasoconstriction induced by P2U receptors. 3) The effects of ATP on pancreatic vessels is dependent on the balance between its vasodilator effect due to the activation of P2Y receptors and its vasoconstrictor effect which involves two types of receptors: P2X and P2U.     

The structural characteristics of the phrenic nucleus in the cat and their functional significance]

The structural elements of phrenic nucleus have been compared under the horseradish peroxidase introduction into the phrenic muscle and using a silver staining method. All the neurons of nucleus have been proposed to be motoneurons. The characteristic features of phrenic nucleus organisation are created by the groups of motoneurons and their dendritic bundles. Each nucleus contains about 800 motoneurons. Their sizes have been determined in three planes. Some functional characteristics of phrenic nucleus on the basis of its structural architecture are under discussion.     

Formation and interrelationship of the activity of several dehydrogenases during rat development]

The specific and general enzymic activity of some dehydrogenases of the liver, kidneys, heart, thymus and spleen was studied on rats in early postnatal period. Some regularities of the development of enzymes under study were established: ergontic correlations of the "maturing" enzymic organ systems and the coordination of the enzymic status of organs and the lymphocytes circulating in the blood. It may be supposed that the lymphocyte is a carrier of information about formation of metabolic processes of the developing organism. The mechanisms of appearance of coordination of the enzymic activity are discussed.