Biomedical subjects

L Borisova

Publications and source records attributed to L Borisova.

9 recordsLinked to original sources

PubMed2004

Rho-kinase inhibition and electromechanical coupling in rat and guinea-pig ureter smooth muscle: Ca2+-dependent and -independent mechanisms.

Recent data have shown Ca(2+)-dependent activation of Rho-kinase by sustained depolarization of arterial smooth muscle. Visceral smooth muscles, however, contract phasically in response to action potentials and it is unclear whether Ca(2+)-dependent or -independent Rho-kinase activation occurs. We have therefore investigated this, under physiologically relevant conditions, in intact ureter. Action potentials, ionic currents, Ca(2+) transients, myosin light chain (MLC) phosphorylation and phasic contraction evoked by action potentials in guinea-pig and rat ureter were investigated. In rat, but not guinea-pig ureter, three Rho-kinase inhibitors, Y-27632, HA-1077 and H-1152, significantly decreased phasic contractions and Ca(2+) transients. Voltage- and current-clamp data showed that Rho-kinase inhibition reduced the plateau component of the action potential, inhibited Ca(2+)-channels and, indirectly, Ca(2+)-activated Cl(-) channels. The Ca(2+) channel agonist Bay K8644 could reverse these effects. The K(+) channel blocker TEA could also reverse the inhibitory effect of Y-27632 on the action potential and Ca(2+) transient. Ca(2+) transients and inward current, activated by carbachol-induced sarcoplasmic reticulum Ca(2+)release, were not affected by Rho-kinase inhibition. Rho-kinase inhibition produced a Ca(2+)-independent increase in the relaxation rate of contraction, associated with acceleration of MLC dephosphorylation, which was sensitive to calyculin A. These data show for the first time that: (1) Rho-kinase has major effects on Ca(2+) signalling associated with the action potential, (2) this effect is species dependent and (3) Rho-kinase controls relaxation of phasic contraction of myogenic origin. Thus Rho-kinase can modulate phasic smooth muscle in the absence of agonist, and the mechanisms are both Ca(2+)-dependent, involving ion channels, and Ca(2+)-independent, involving MLC phosphorylation activity.

Action Potentials↗

PubMed2002

Characterisation of the ionic currents in freshly isolated rat ureter smooth muscle cells: evidence for species-dependent currents.

To better understand excitability, and hence contraction, the ionic currents underlying the action potential were identified and characterised in enzymatically isolated smooth muscle cells of the rat ureter. Using the whole-cell patch-clamp, under voltage-clamp conditions with K(+) in the pipette, three types of responses occurred to depolarisation: (1) sustained outward current and spontaneous transient outward currents (STOCs); (2) inward current; and (3) fast outward current. Investigation using different voltage protocols and pharmacological blockers and agonists revealed the presence of three outward and two inward currents. The outward currents were: (1) a sustained BK current, sensitive to low concentrations of tetraethylammonium (TEA) and featuring bursts of STOCs superimposed on it; (2) a fast, transient, A-type K current sensitive to 4-aminopyridine; and (3) a TEA and Ca(2+)-insensitive, late K(+) rectifier current. The inward currents were: (1) a fast L-type Ca(2+) channel current sensitive to nifedipine, Cd(2+) and potentiated by Ba(2+); and (2) a Ca(2+)-sensitive Cl(-) channel, which was inhibited by niflumic acid and Ba(2+), and produced a large tail current upon repolarisation at the end of the voltage step. The I- V relationships and peak amplitudes of all the currents are described. The finding of a K(+) rectifier and Ca(2+)-activated Cl(-) channel distinguish the rat ureteric cells from those of the guinea-pig. Thus, as well as the previously established difference in sarcoplasmic reticulum Ca(2+)-release mechanisms, there is also a species difference in ion channel expression in this tissue. We relate these currents to their possible contribution to the characteristically extremely long lasting action potential in the rat ureter.

4-Aminopyridine↗

PubMed1987

[SH group content and hydrolase activity of the small intestine mucosa in chickens fed a mixture containing aflatoxin B1].

The effect of aflatoxin B1 on the content of SH-groups and the activity of leucinamino peptidase, Mg (Na+, K+), ATP, and glucoamylase in the mucous membrane of the small intestine of birds was studied. The experiment was carried out with three groups of male broilers. The controls were given starter and finisher mixtures with 21.6 and 19.5 per cent protein, with no aflatoxin B1. The birds of the test groups (II and III) were offered one and the same mixture containing 0.250 and 0.600 ppm of aflatoxin B1. By the end of the finisher period on the 49th day mucosa homogenate was used to determine the content of SH-groups and the activity of leucinamino peptidase, Mg (Na+, K+), ATP, and glucoamylase. It was found that rates of 0.600 ppm in the feed suppressed the activity of Mg (Na+, K+) ATP in the mucosa of the small intestine. Lower amounts (0.250 ppm) produced no effect on the activity of this enzyme. Leucinamino peptidase, glucoamylase, and the SH-groups did not change essentially their activity at the two rates of the toxin.

Aflatoxin B1↗

PubMed1987

[Experimentally induced aflatoxicosis in broilers].

Aflatoxicosis was induced under experimental conditions in two groups of broiler birds fed in the course of the entire fattening period upon feed, containing 0,250 and 0,600 ppm aflatoxin. Dependable changes were established in the investigated haematological and biochemical indices. There was a drop of the body weight and an increase in the feed to gain ratio. Pathologic changes were recorded in the liver.

Animal Feed↗

PubMed1985

[Paraclinical research on broiler chickens treated with aflatoxin B1 and microbiological studies of the meat and liver obtained from them].

Studied were some paraclinical indices of the blood of 50 broiler birds treated with aflatoxin B1. It was found that the effect of the mycotoxin used in concentrations of 25.0 and 37.5 micrograms in the course of thirty days and in conc. of 50.0 micrograms in the course of five days with three test groups of birds (as compared to a group of controls) consisted in the drop of total protein and the rise of the activity of GOT, GPT, and total bilirubin. It was demonstrated that the use of feeds containing aflatoxin B1 had a bearing on the microbiologic status of the meat and liver. There was no increase in the total count of aerobic mesophile organisms.

Aflatoxin B1↗

PubMed1981

[Clinical, morphological and biochemical changes in lambs caused by Fusarium toxins].

Studied was the effect of toxic trichotecenes and the F-2 toxin on the health status and the morphologic and biochemical changes in the blood on weaned lambs. It was shown that there was a drop of the hemoglobin content, rise of the leucocyte count, and decrease in the amount of the total proteins along with an increase in the activity of glutamate-oxalacetate and glutamate-pyruvate transaminases, alkaline phosphatase, and lactate-dehydrogenase. The morphologic changes appeared confined to the rumen, lymph nodes of the forestomach, duodenal mucosa, liver, and kidneys.

Animals↗

PubMed1981

[Clinical, morphological and biochemical changes in pigs caused by the toxic metabolites of Fusarium tricinctum].

Experiments were carried out with pigs in the course of 30 days with the use of dietary mixtures containing 10 and 20 per cent cultures of Fusarium tricinctum in rice. The treated animals showed higher sensitivity to trichotecenes. These moulds metabolites raised the activity of the serum glutamate oxaloacetate and glutamate-pyruvate transaminases, aldolase, lactate dehydrogenases, alkaline phosphatase, lipid level, and leukocyte count but lowered the amount of total protein and that of hemoglobin. The morphologic lesions seemed confined mainly to the stomach, intestines, and kidneys.

Animals↗

PubMed1975

[Influence of ammonia gas on indices of protein metabolism in broilers].

The effect was studied of various concentrations of ammonia (5, 20, 50 and 100 ppm) on 20-day old chicken broilers for 120 min. The birds were killed in order to study the protein content in the liver, heart musculature, and blood serum as well as the content of the free amino acids and tryptophane. Followed up was also the transaminase activity of the liver and heart musculature and the activity of GOT and GPT. It was established that ammonia does not alter the content of proteins in the investigated organs and blood serum. A dependable increase in the concentration of the free amino acids in the blood serum observed. Under the effect of 50 and 100 ppm there was no decrease in the tryptophane content of the liver and the blood serum. High concentrations of ammonia decreased the transamimase activity of the liver and heart and raised the activity of the serum GPT.

Alanine Transaminase↗

PubMed1975

[Efficacy of aerosol disinfection with lactic acid and its effect on the body of poultry].

Comparative studies were carried out to establish the efficacy of lactic acid as a disinfection means. The following pattern was observed in employing the agent: a 20 per cent conc. of the acid at the rate of 20 cu. cm per cubic meter is dispersed three times as an aerosol (at 8, 12, and 6 oclock) in the course of twenty minutes. It was found that the microbial contamination of the air drops three to four times. More pronounced is the bactericidal effect on the coliforms and moulds. The birds of the group treated with lactic acid gain 30 g more per day up to the end of the fattening period. Dependable is the higher serum level of protein as well as the higher protein content of the liver and heart musculature and of the essential amino acid tryptophane in the blood serum and liver of the test birds. Higher was also the glycogen content of the liver of the test group broilers.

Aerosols↗