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Biomedical subjects

J F Tallman

Publications and source records attributed to J F Tallman.

18 recordsLinked to original sources
PubMed1979

Modulation of benzodiazepine binding site sensitivity.

Recent studies on agents which alter benzodiazepine binding site sensitivity in brain are described. GABAergic agonists enhance and antagonists inhibit binding to the brain specific benzodiazepine binding site, and the binding can be correlated with effects on neuronal cell firing in the dorsal raphe nucleus. Anions such as chloride, iodide and nitrite also enhance (3H)diazepam binding and this enhancement is consistent with their role in postsynaptic inhibition. Pretreatment of animals with the anticonvulsant, diphenylhydantoin, enhances both diazepam binding and the electrophysiological response to diazepam suggesting one possible locus for the anticonvulsant action of diphenylhydantoin in brain. Taken together, these results suggest the existence of a GABA/Cl- ionophore/BZ binding complex in brain. Preliminary results on the purification of the BZ component of this complex and fluorescent probes for its study are described.

Aminooxyacetic Acid↗
PubMed1979

Adrenergic receptor function is different in male and female patients with essential hypertension.

As plasma norepinephrine (NE) levels may be similar in hypertensive and normotensive subjects, the sensitivity of adrenergic receptors was investigated in patients with essential hypertension and normotensive subjects of similar age and sex. Alpha-adrenergic receptor sensitivity was measured in platelets by the specific binding of [3H]dihydroergocryptine and the NE inhibition of prostaglandin E1 (PGE1)-stimulated cyclic AMP (cAMP) production. The number of alpha-adrenergic receptors in platelets from hypertensive women was 1.5 times that in the platelets from normotensive ones, with no differences between hypertensive and normotensive women or between men and women in the affinity of the alpha-adrenergic receptor for [3H]dihydroergocryptine. PGE1-stimulated cAMP production was half as great in hypertensive as in normotensive men, while NE inhibition of PGE1-stimulated cAMP production was similar in hypertensive and normotensive men and women. [3H]Dihydroergoeryptine binding in female hypertensives, and PGE1-stimulated cAMP in male hypertensives did not differ from that in sex-matched controls. The sensitivity of the beta-adrenergic receptor, measured by [3H]dihydroalprenolol binding and cAMP production was similar in hypertensive and normotensive subjects.

Cyclic AMP↗
PubMed1978

Properties of beta-adrenergic receptors in untreated and butyrate-treated Hela cells.

HeLa cells contain receptors on their surface which are beta-adrenergic in nature. The binding of (-)-[3H]dihydroalprenolol is rapid, reversible, stereospecific and of relatively high affinity. The HeLa cells also contain an adenylate cyclase which is activated by (-)-isoproterenol greater than (-)-epinephrine greater than (-)-norepinephrine. The adenylate cyclase of HeLa is also activated by guanyl-5'-ylimidodophosphate (Gpp(NH)p), a nonhydrolyzable analogue of GTP. Inclusion of both (-)-isoproterenol and Gpp(NH)p leads to approximately additive rather than synergistic activation of adenylate cyclase. After treatment of HeLa cells with 5mM sodium butyrate there is an increase in the number of beta-adrenergic receptors, but not in their affinity, which is reflected in an increased ability of (-)-isoproterenol to activate adenylate cyclase. Other properties of the beta-adrenergic receptor including association and dissociation rates, temperature optimum of adenylate cyclase and response to Gpp(NH)p are relatively unaffected by butyrate pretreatment of the cells.

Adenylyl Cyclases↗
PubMed1977

Induction of functional beta-adrenergic receptors in HeLa cells.

HeLa cells contain beta-adrenergic receptors that are characterized by specific binding of I[3H]dihydroalprenolol, increased 3':5'-cyclic AMP production in intact cells after incubation with l-isoproterenol, and increased adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] activity in the presence of l-isoproterenol. After cells were cultured with butyrate, the number of beta-adrenergic receptors, cyclic AMP production in intact cells, and adenylate cyclase activation by l-isoproterenol were increased severalfold over those of untreated cells. The increase involved the induction of synthesis of new receptor molecules with identical affinities for l-[3H]-dihydroalprenolol; all three processes were blocked by cycloheximide and actinomycin D. This induction was relatively specific for butyric acid and only the closely related short-chain fatty acids, propionic and valeric acids, were capable of partially inducing the same effect. In contrast to induction of beta-adrenergic binding sites, there was no increase in basal or fluoride-activated adenylate cyclase activity, indicating that the beta-adrenergic receptor and adenylate cyclase and different molecules that may be controlled separately.

Adenylyl Cyclases↗
PubMed1976

Biosynthesis and metabolism of endogenous tyramine and its normal presence in sympathetic nerves.

By use of a sensitive and specific enzymatic isotopic method for the determination of tyramine, the small quantities of this amine which are present endogenously in rat tissues, including brain, heart, kidney and salivary gland, have been quantitated. The levels of tyramine in brain were increased to a similar extent by injecting animals with a monoamine oxidase inhibitor, pargyline, and a dopamine beta-hydroxylase inhibitor, FLA-63; in contrast, pretreatment of animals with alpha-methyl-para-tyrosine, a tyrosine hydroxylase inhibitor, did not lead to an increase in tyramine levels in brain. Pretreatment of rats with 6-hydroxydopamine resulted in a marked diminution in the tyramine content of rat atria and salivary gland. Denervation of the salivary gland decreased the endogenous level of tyramine approximately 50% in denervated glands compared to undenervated glands. These results suggest that tyramine exists at least partly in sympathetic nerves in many tissues.

Animals↗
PubMed1975

Deficient Ganglioside Biosynthesis: a novel human sphingolipidosis.

An unusual lipid storage disese is chracterized by the accumulation of hematoside (Gms3) in the patient's liver and brain. In contrast to the other sphingoliidoses, the accumulation of Gm3 is not the result of a defective catabolic reaction, but is the first disorder caused by deficiency in ganglioside biosynthesis to be described in man.

Brain↗