Biomedical subjects

U C Garg

Publications and source records attributed to U C Garg.

43 records · Page 3Linked to original sources

PubMed1987

Role of Ca2+/calmodulin in the regulation of sugar uptake in Escherichia coli heat-stable enterotoxin induced diarrhoea in mice.

The mucosal-to-serosal fluxes of 3-O-methyl-D-glucose, a non-metabolizable analogue of D-glucose, were carried out in control and heat-stable enterotoxin treated mice in the presence or absence of Ca2+-ionophore, Ca2+-channel blocker, calmodulin inhibitor and Na+-K+-ATPase inhibitor. The transport of the sugar was significantly decreased (p less than 0.01) in the experimental animals. In the presence of Ca2+-ionophore, the uptake of the sugar decreased significantly (p less than 0.01) only in the control group while experimental group remained unaffected. Ca2+ channel blocker and calmodulin inhibitor significantly increased (p less than 0.01) the uptake of sugar in both the groups, however, the changes were more pronounced in the experimental group. Ouabain blocked the uptake of the sugar in both the groups. These studies indicated that heat-stable enterotoxin inhibit Na+-K+-ATPase by increasing Ca2+ uptake and calmodulin activity, thus resulting in decreased uptake of 3-O-methyl-D-glucose in heat-stable enterotoxin treated mice.

3-O-Methylglucose↗

PubMed1987

Towards the mechanism of altered nutrients uptake in renal brush border membrane vesicles from pyelonephritic rats.

Affinity constant (Km) of D-glucose, L-alanine, L-aspartate, L-lysine, L-proline and nutrients coupled Na+ were determined in renal brush border membrane vesicles prepared from control and pyelonephritic rats. The Km of D-glucose, amino acids and nutrients coupled Na+ was noted to be significantly increased (p less than 0.001) in experimental animals. The Vmax of D-glucose and amino acids was determined at different concentrations of nutrients keeping extravesicular Na+ constant or at different concentrations of extravesicular Na+ keeping nutrient concentration constant. In the experimental rats the Vmax decreased significantly (p less than 0.01) when compared to control. The increased Km and decreased Vmax may be one of the underlying mechanism leading to decrease in the uptake of D-glucose and amino acids.

Amino Acids↗

PubMed1987

Intestinal brush border calmodulin: key role in the regulation of NaCl transport in Giardia lamblia infected mice.

Activity of calmodulin and uptake of Ca2+, Na+ and Cl- was studied in control and Giardia lamblia infected mice. The activity of calmodulin was found to be significantly increased (p less than 0.001) in the experimental group as compared to control group. The uptake of Ca2+ increased significantly (p less than 0.001) while that of Na+ and Cl- decreased (p less than 0.001) in brush border membrane (BBM) vesicles from experimental group as compared to control group. In the presence of calmodulin inhibitor, trifluoperazine (TFP), the transport of Na+ and Cl- increased significantly (p less than 0.05) as compared to in the absence of inhibitor while transport of Ca2+ remained unaltered.

Animals↗

PubMed1986

Renal nutrients uptake and brush-border membrane enzymes in cholesterol-fed guinea pigs.

The effect of dietary cholesterol load on the reabsorption of nutrients and the enzyme and chemical characteristics of renal brush-border membrane (BBM) was evaluated in guinea pigs. The transport of D-glucose and amino acids into the renal BBM vesicles of experimental animals was significantly (P less than 0.001) decreased. Vmax of leucine aminopeptidase decreased without alteration in Km; however, both the Km and Vmax of alkaline phosphatase and maltase decreased in renal membrane in response to cholesterol load. The alterations in the chemical architecture of the membrane could possibly be responsible for the observed aberrations in the kidneys of cholesterol-fed animals.

Amino Acids↗

PubMed1986

Enzymatic and transport studies in cholesterol-fed guinea pigs using intestinal brush border membrane vesicles.

The intestinal absorptive and digestive functions using the brush border membrane (BBM) vesicles were evaluated in guinea pigs receiving cholesterol-supplemented diet for 12 weeks. The Na+-gradient-dependent transport of D-glucose (p less than 0.001), L-alanine and L-phenylalanine (p less than 0.01) was decreased significantly the BBM of cholesterol-fed animals. The maximal velocity (Vmax) value of the sucrase and leucine aminopeptidase was decreased without any change in the affinity constant (Km) value, demonstrating that the enzyme contents were reduced in response to cholesterol-rich diet. However, both the Km and Vmax values of the alkaline phosphatase decreased markedly, suggesting that a new enzyme of increased substrate affinity had been formed due to intestinal adaptation of cholesterol load in diet. The present study demonstrated that cholesterol feeding caused a significant alteration in nutrients absorption, membrane enzymes and chemical composition of the small intestine.

Alanine↗

PubMed1986

Kinetics of reabsorption of nutrients in renal brush border membrane vesicles from rats with experimental ascending pyelonephritis.

The uptake of nutrients was investigated in the renal cortical brush border membrane (BBM) vesicles at different stages of ascending pyelonephritis. There was significant difference (p less than 0.05) in the uptake of D-glucose, L-alanine, L-aspartate, L-lysine and L-proline 3 days postinfection and onwards in both right unobstructed and left obstructed experimental kidneys as compared to the sham operated control. The uptake of D-glucose, L-lysine and L-proline was found to be significantly decreased (p less than 0.05) during the course of infection. While uptake of L-alanine and L-aspartate increased (p less than 0.05) in early stages and decreased (p less than 0.05) in later stages of infection. The differential effect was attributed to the compensatory measure and different kinds of transport systems for different types of amino acids.

Amino Acids↗

PubMed1985

Pyelonephritis alters the reabsorption of nutrients and brush border membrane enzymes of rat kidney.

The uptake of nutrients and activities of membrane enzymes in the kidney were investigated using renal brush border membrane (BBM) vesicles in acute pyelonephritis in rats. A significant decrease (P less than 0.001) in the uptake of D-glucose and L-phenylalanine was observed in both the unobstructed right and obstructed left kidney, while there was a significant increase (P less than 0.001) in the uptake of L-alanine in the left kidney of pyelonephritic rats, demonstrating disturbances in the reabsorption of the glucose and aminoacids in the kidneys. Vmax of alkaline phosphatase, leucine-amino-peptidase and maltase was found to be decreased in the left kidney, suggesting that there was a reduction in the active enzyme molecule number. Km of alkaline phosphatase and leucine-aminopeptidase remained unchanged, while km of maltase decreased in both the right and left kidneys. An increase in the Vmax of alkaline phosphatase and leucine-aminopeptidase and substrate affinity of the maltase in the right kidney demonstrated a compensatory phenomenon for the malfunctioning of the left kidney. This is the first report demonstrating alterations in reabsorption of nutrients and BBM enzymes in experimental pyelonephritis.

Absorption↗