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Biomedical subjects

S P Banerjee

Publications and source records attributed to S P Banerjee.

At least 55 records · Page 3Linked to original sources
PubMed1977

Muscarinic cholinergic receptors in rat heart. Effects of thyroidectomy.

The effects of thyroid status on muscarinic cholinergic receptors in the rat myocardium were investigated. The potent muscarinic antagonist [3H]quinuclidinyl benzilate was used to identify muscarinic cholinergic receptors in rat heart particulate fractions from control, hypothyroid, and hyperthyroid rats. Thyroidectomy increased specific [3H]quinuclidinyl benzilate binding to heart particulate fractions by about 60% as compared to euthyroid rat cardiac preparations. Administration of triiodothyronine to euthyroid rats decreased specific binding to muscarinic cholinergic receptors by about 20%. Scatchard analysis revealed that the cardiac particulate fraction from thyroidectomized rats contained 134 fmol of [3H]quinuclidinyl benzilate binding sites per mg of protein, as compared with 85 fmol/mg of protein found in the heart preparation of thyroidectomized rats chrinically treated with triiodothyronine. The equilibrium dissociation constant for the interaction of receptors with quinuclidinyl benzilate was the same (1 nM) in the heart particulate fractions derived from these two groups of rats. The results of this study demonstrate that thyroid hormone can regulate the number of cardiac muscarinic cholinergic receptors. Thus, the parasympathetic nervous system may participate in the cardiovascular abnormalities in different thyroid states.

Animals↗
PubMed1977

[3H]-ouabain binding to denervated and innervated skeletal muscle.

In cat skeletal muscles, the major part of specific [3H]-ouabain binding was found in the sympathetic nerve endings of red, slow muscle fibres. Skeletal muscle denervation increased specific [3H]-ouabain binding to muscle membrane preparation. This increase may be involved in the development of spontaneous fibrillation in the denervated muscle.

Adenosine Triphosphatases↗
PubMed1977

Inhibition of [3H]norepinephrine uptake in peripheral organs of some mammalian species by ouabain.

In order to demonstrate the possible involvement of (Na+ + K+)-ATPase in the high affinity uptake of [3H]-norepinephrine in the sympathetic nerve endings, the effect of ouabain on [3H]norepinephrine uptake in spleen and heart slices of five mammalian species was examined. The ouabain sensitivity of [3H]norepinephrine uptake in the heart slices form various species, as determined by the estimation of IC52, was, in increasing order, lamb (2,3 muM) less than calf (2.5 muM) less than guinea pig (4 muM) less than rabbit (10muM) less than rat (greater than 500 muM). The IC50 values in the spleen slices were: lamb (1 muM) less than calf (3.2 muM) less than rabbit (9.5 muM) less than guinea pig (25 muM) less than rat (greater than 500 muM). The IC50 values for the inhibition of specific [3H]ouabain binding in the microsomal fractions of spleen and heart of the five mammalian species by ouabain were similar to the IC50 values for the inhibition of [3H]norepinephrine uptake by the cardiac glycoside. Since ouabain is known to bind exclusively to (Na+ + K+)-ATPase of a microsomal fraction, these results suggest that the inhibition of [3H]norepinephrine uptake in the sympathetic nerve endings by ouabain is mediated by the inhibition of (Na+ + K+)-ATPase.

Animals↗
PubMed1976

Solubilization of nerve growth factor receptors of rabbit superior cervical ganglia.

Nerve growth factor (NGF) receptors of rabbit superior cervical ganglia can be solubilized by treatment with detergents and readily assayed in the soluble state. Triton X-100 and deoxycholate reduce specific binding of NGF to ganglia membranes. In membranes treated with Triton X-100 (0.5 to 2.0%) the reduction in NGF binding by membranes is accompanied by a corresponding increase in binding in the supernatant fluid. NGF binding in soluble preparations can be rapidly assayed by precipitating NGF bound to receptors with polyethylene glycol under conditions in which unbound NGF is not precipitated. NGF binding to soluble preparations is saturable whether evaluated by the binding of 125I-NGF or by diluting 125I-NGF with native NGF. Using both techniques, the dissociation constant for NGF binding to soluble receptors is about 0.2 nM, the same as its dissociation constant from receptor sites in intact membranes. NGF binding to soluble receptors displays a high degree of peptide specificity, similar to receptor sites in intact membranes of superior cervical ganglia. A method of labeling NGF with 125I-3(4-hydroxyphenyl) propionic acid N-hydroxysuccinimide ester is described which leads to binding properties that are superior to those obtained with previously described 125I-NGF preparations.

Animals↗
PubMed1976

Increased nerve-growth-factor beta-chain cross-reacting material in familial dysautonomia.

To determine whether dysautonomia arises from alteration in nerve-growth factor (NGF), we measured serum levels of NGF subunits in normal and dysautonomic subjects using a biologic assay based on neurite outgrowth from chick ganglions, a binding assay based on displacement of radiolabeled betaNGF from rabbit-ganglion microsomes, and radioimmunoassays of chi, gamma and betaNGF subunits via antiserum to mouse NGF polypeptides. A threefold increase (P less than 0.001) in serum antigen levels of the biologically active subunit (betaNGF) was found for dysautonomic as compared with normal subjects. By all other assays, the groups were alike. The marked discrepancy in betaNGF levels between antigenic and functional (biologic and binding) measurements suggests a qualitative abnormaltiy of betaNGF in dysautonomia. Alternatively, elevation of betaNGF antigen can be regarded as secondary to disease. This alternative seems less likely since we must then suppose that the normalcy of functional assays in spurious.

Adolescent↗
PubMed1975

Nerve growth factor receptor binding. Influence of enzymes, ions, and protein reagents.

Nerve growth factor (NGF) receptor binding in membrane fractions of rabbit superior cervical ganglia has been measured after treatment with a variety of enzymes, protein-modifying reagents, and ions. Receptor binding is degraded by low concentrations of trypsin but is much less sensitive to alpha-chymotrypsin. Low concentrations of phospholipase A from Vipera russelli decrease NGF receptor binding by lowering the number of binding sites, while phospholipase A preparations from Crotalus terrificus terrificus and bee venom do not affect binding. Phospholipase C and D, neuraminidase, DNase, and RNase have minimal effects on receptor binding. NGF receptor binding appears to be absolutely dependent upon calcium ion. Removal of calcium from the incubation medium greatly reduces binding as does treatment with EDTA. Maximal receptor binding occurs at 5 mM calcium. Magnesium and sodium are unable to substitute for calcium. Receptor binding is greatly reduced by treating membranes with 2-hydroxy-5-nitrobenzyl bromide, 2-methoxy-5-nitrobenzyl bromide, diazonium tetrazole, and tetranitromethane. NGF receptor sites can be protected from 2-hydroxy-5-nitrobenzyl bromide by incubation with NGF.

Animals↗
PubMed1975

Cannabinoids: influence on neurotransmitter uptake in rat brain synaptosomes.

We have examined the effect of Delta1-tetrahydrocannabinol (delat1-THC) and 12 of its derivatives on the uptake of 3H-labeled norepinephrine (NE), dopamine (DA), serotonin (5-HT) gamma-aminobutyric acid (GABA) into synaptosomes in homogenates of various regions of rat brain. Delta1-THC inhibits the accumulation of NE and 5-HT into hypothalamic preparations and DA into the corpus striatum with Ki values of about 12 to 25 muM while GABA uptake into cerebral cortical preparations is inhibited less (Ki = 140 muM). The affinities of delta6-THC, 7-hydroxy-delta1-THC, 7-hydroxy-delta6-THC and cannabidiol for 5-HT, NE and GABA transports are similar to values for delta1-THC, while cannabigerol, cannabinol and delta6-THC-7-oic acid have substantially less affinity. Thus, hydroxylation of C-7 in delta6-THC does not alter inhibitory potency, but its oxidation to an acid and aromatization of ring A greatly reduce affinity. The hydroxyl at C-3(1) of ring C is critical for inhibition of NE, 5-HT and GABA uptake, since its acetylation or methylation abolishes activity. Inhibition of NE, DA, 5-HT and GABA uptake by all cannabinoids examined is noncompetitive. Only about 1% of delta1-THC and delta6-THC and 5% of cannabidiol are fully soluble under our experimental conditions.

Acetylation↗