In pursuit of the α‐adrenoceptor: a fine‐structural and electron autoradiographic study using <sup>3</sup>H‐phenoxybenzamine and smooth muscle from the cat and guinea‐pig

Graham, J. D. P.; Ivens, C; Lever, J. D.; McOUISTON, R.; Spriggs, T. L. B.

doi:10.1111/j.1476-5381.1971.tb08028.x

Cited by 10 publications

(2 citation statements)

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“…Although data on phenoxybenzamine distribution in pancreatic beta cells is not available, distribution studies have been done on the smooth muscle cells of the vas deferens. 25 After a fifteen minute exposure in vitro to H-3-phenoxybenzamine, radioactivity was widely distributed over the cytoplasm and nuclei of the smooth muscle cells. This intracellular distribution was probably specific for the alpha adrenergic receptors, as prior exposure to norepinephrine markedly decreased H-3-phenoxybenzamine uptake into the cell.…”

Section: Discussionmentioning

confidence: 99%

Potentiation of Insulin Secretion in Vitro by Serotonin Antagonists

Feldman

Quickel

1972

Diabetes

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The present studies were designed to determine if endogenous pancreatic islet cell monoamines such as serotonin, dopamine and norepinephrine play a physiological role in controlling insulin secretion. With an in vitro rabbit pancreas system, the effects of both serotonin and catecholamine antagonists on basal and stimulated insulin release were studied. Methysergide maleate (Sansert) potentiated both glucose and tolbutamide-stimulated insulin secretion, but alone it had no effect on insulin release. Studies in which exogenous monoamines were added to the incubations demonstrated that methysergide, purported to be a specific serotonin antagonist, blocked inhibition of insulin secretion by dopamine, 1-norepinephrine, 1-epinephrine and 1-isoproterenol. Methysergide differed in action from the alpha adrenergic blocking drug, phenoxybenzamine, for although the latter was a more potent blocker of the inhibitory action of exogenous catecholamines on insulin secretion, it did not potentiate glucose-stimulated insulin secretion. Glucose-mediated insulin secretion was also potentiated by the serotonin antagonists, cinanserin and cyproheptadine. Exogenous serotonin (4 x 10" 3 M) had only a weak action in inhibiting insulin secretion from rabbit pancreas. Methysergide (1 x 10" 4 M) failed to block this inhibitory action. It is suggested that (1) serotonin antagonists are blocking the inhibitory action of an intracellular compartmentalized serotonin pool, (2) some other endogenous indoleamine is the inhibitory substance that is being blocked by the serotonin antagonists, or (3) the three ser.otonin antagonists are influencing glucose-mediated insulin release through some unknown mechanism that has nothing to do with serotonin. DIABETES 21: 779-88, July, 1972. Pharmacological doses of biogenic amines such as epinephrine, 1 ' 2 norepinephrine, 3 dopamine 4 and serotonin 5 ' 7 are potent inhibitors of pancreatic insulin secretion. Because such agents must be used in supraphysiologic quantities to exert this effect, many investigators have questioned the physiological significance of endo-

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Section: Discussionmentioning

confidence: 99%

Potentiation of Insulin Secretion in Vitro by Serotonin Antagonists

Feldman

Quickel

1972

Diabetes

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“…Labeled dibenamine itself, however, is non-specific in a chemical sense and radioactivity was found in all of the subcellular fractions in these experiments as was suggested in the case of a-adrenergic receptor labeling (26,27). Radioactivity difference was, however, localized mainly in the cell membrane.…”

Section: Discussionmentioning

confidence: 77%

Purification of Histamine Receptor (III) Characterization of Receptor Rich Membrane Fraction of Small Intestinal Smooth Muscle of the Cat

Uchida

Takagi

1977

Japanese Journal of Pharmacology

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Abstract-Intracellular localization of histamine receptors in small intestinal smooth muscle of the cat was studied by investigating distribution of marker enzymes in the receptor rich fraction.Distribution of membrane markers coincided with that of the radiochemically labeled receptor fraction. Membrane fraction was further purified and it was concluded that the histamine receptor rich fraction is mainly composed of cell membrane.The chemical composition of the fraction lent support to this conclusion.In our previous papers (1, 2) we reported data on the fractionation of histamine receptors of small intestinal smooth muscle in the cat. The radioactivity difference were investigated between the muscle labeled with radioactive dibenamine under protection with specific or non-specific drugs and the muscle without protective drugs. The fraction was obtained in which specifically labeled histamine receptors were concentrated. The specificity of the fraction was proved by examining the pattern of distribution of radioactivity differences in subcellular fractions of the muscle protected with specific drugs or with non-specific drugs which did not protect histamine receptors pharmacologically but did provide radiochemical protection. The present work deals with intracellular localization of histamine receptors in relation to distribution of enzymatic activities and the biochemical nature of histamine receptor rich fraction is discussed.

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Cellular Aspects of Catecholaminergic Neurons

Geffen

Jarrott

1977

Comprehensive Physiology

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In pursuit of the α‐adrenoceptor: a fine‐structural and electron autoradiographic study using ³H‐phenoxybenzamine and smooth muscle from the cat and guinea‐pig

Cited by 10 publications

References 9 publications

Potentiation of Insulin Secretion in Vitro by Serotonin Antagonists

Potentiation of Insulin Secretion in Vitro by Serotonin Antagonists

Purification of Histamine Receptor (III) Characterization of Receptor Rich Membrane Fraction of Small Intestinal Smooth Muscle of the Cat

Cellular Aspects of Catecholaminergic Neurons

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In pursuit of the α‐adrenoceptor: a fine‐structural and electron autoradiographic study using 3H‐phenoxybenzamine and smooth muscle from the cat and guinea‐pig

Cited by 10 publications

References 9 publications

Potentiation of Insulin Secretion in Vitro by Serotonin Antagonists

Potentiation of Insulin Secretion in Vitro by Serotonin Antagonists

Purification of Histamine Receptor (III) Characterization of Receptor Rich Membrane Fraction of Small Intestinal Smooth Muscle of the Cat

Cellular Aspects of Catecholaminergic Neurons

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In pursuit of the α‐adrenoceptor: a fine‐structural and electron autoradiographic study using ³H‐phenoxybenzamine and smooth muscle from the cat and guinea‐pig