Characteristics of (3H)E-643-binding to alpha adrenoceptors.

Hata, Fumiaki; Kondo, Etsuo; Kondo, Shigeru; Kagawa, Kimiya; Ishida, Hideyuki

doi:10.1254/jjp.32.181

Cited by 36 publications

(13 citation statements)

References 21 publications

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“…In the present study, bunazosin, a potent and highly selective alpha-1 antagonist (19,20), dose-dependently inhibited NE and PE induced vasoconstrictions in both dog and monkey lingual arteries. However, NE and PE-induced responses were not suppressed by midaglizole, which is a preferential and speci fic alpha-2 antagonist (15).…”

Section: Discussionsupporting

confidence: 51%

Pharmacological Features of Vascular Responses of Isolated Dog and Monkey Lingual Arteries to Vasoactive Substances

Škrbić

Chiba

1991

Japanese Journal of Pharmacology

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ABSTRACT-Using a perfusion technique of isolated vessels, vasoconstrictor re sponses to alpha adrenoceptor agonists (norepinephrine [NE], phenylephrine [PE], clonidine, xylazine and tyramine) and KCI were investigated in isolated, perfused dog and monkey lingual arteries. A stainless steel cannula was inserted into the lingual artery segment and perfused with Krebs-Henseleit solution at a constant flow rate. In dog lingual avteries, the agonists induced vasoconstrictions with the following order of potency: NE > PE > tyramine >> clonidine > xylazine > KCI. In monkey prepara tions, the order was NE > PE >> clonidine >_ tyramine > xylazine > KC1. In both preparations, NE and PE-induced constrictions were blocked by bunazosin (an alpha 1 adrenoceptor antagonist), but not influenced by midaglizole (a potent alpha-2 anta gonist). Diltiazem (a Ca entry blocker) significantly attenuated NE-induced vasocon strictions in dog lingual arteries, but did not significantly influence these in monkey preparations. These results suggest that: [1] these arteries contain mostly alpha-1 but scarcely any alpha-2 adrenoceptors; [2] in dog preparations, tyramine induced a marked vasoconstriction which may contribute to investigation on the mechanisms of catecholamine releases from sympathetic nerve terminals; and [3] different blocking effects of diltiazem may indicate that extracellular Ca + + influx may have varying de grees of importance in alpha-1 adrenoreceptor-mediated constrictions in different spe cies, although participation of an intracellular mechanism might not be ruled out.

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Section: Discussionsupporting

confidence: 51%

Pharmacological Features of Vascular Responses of Isolated Dog and Monkey Lingual Arteries to Vasoactive Substances

Škrbić

Chiba

1991

Japanese Journal of Pharmacology

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“…The order of potency of the four agents was NA > phenylephrine > clonidine > methoxamine > xylazine. Bunazosin, a highly selective a,-adrenoceptor antagonist (24,25), dose dependently inhibited the vasoconstrictive responses to clonidine and NA. However, midaglizole, a specific a2-an tagonist (26), did not significantly affect the vasoconstric tive responses to NA and clonidine, except for the slight but significant inhibition by 300 nmol midaglizole of the vasoconstrictive response to 3 nmol clonidine.…”

Section: Effects Of Vasoactive Agentsmentioning

confidence: 99%

Characteristics of the Responses of Isolated and Perfused Canine Splenic Arteries to Vasoactive Substances and to Periarterially Electrical Stimulation

Ren

Nakane

Chiba

1994

Japanese Journal of Pharmacology

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ABSTRACT-Pharmacological characteristics of the canine isolated splenic artery were investigated by the cannula insertion method for observing vascular responses to vasoactive agents and periarterial nerve stimulation. Four a-adrenoceptor agonists and tyramine induced vasoconstrictions in a dose-dependent manner, and the order of potency was noradrenaline (NA) > phenylephrine > clonidine > methoxamine > tyramine. Xylazine (a selective a2-adrenoceptor agonist) did not elicit any vasoconstriction. Several autacoids and KCl also constricted the splenic artery dose-dependently, and the order of potency was 5 hydroxytryptamine (5-HT) > ATP = histamine > KCI. The dose-response curves for clonidine and NA were shifted to the right by bunazosin (a selective a,-adrenoceptor antagonist), but were not affected by midaglizole (a selective a2-adrenoceptor antagonist). The parameters of electrical stimulation to elicit a clear and constant vasoconstriction were 0.2 msec of pulse duration, 6 V and 0.1 Hz. The vasoconstrictive responses to electrical stimulation at 6-12 V, 0.1-10 Hz and 0.2-1 msec of pulse duration were completely inhibited by tetrodotoxin (TTX) and strongly inhibited by guanethidine. The results in this study suggest that: 1) in contrast with other regional arteries, the canine splenic artery has an a 1-adrenoceptor-related and clonidine-sensitive vasoconstrictive response, 2) this artery has no functional postsynaptic a2-adrenocep tors, 3) it may be easier to observe the vascular responses to vasoactive agents in the isolated and perfused arterial segments, and 4) the isolated and perfused canine splenic artery is useful as a preparation to study the sympathetic nerve transmission.

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“…However, the grain density in the epithelial regions was lower than that in the stroma. bunazosin is a potent postsynaptic al-blocker with a higher selectivity than that of prazosin (13,14), [3H]-bunazosin should also be a useful ligand for binding assays (3,13,14). The al-adrenoceptors in the prostate were reported to be localized in the stroma by Chappel et al (2) and James et al (4).…”

Section: Whenmentioning

confidence: 99%

Demonstration of .ALPHA.1-adrenoceptors in human hypertrophied prostate with tritiated bunazosin.

Moriyama

Kawabe

Hamada

et al. 1991

Acta Histochem. Cytochem

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Characteristics of (3H)E-643-binding to alpha adrenoceptors.

Cited by 36 publications

References 21 publications

Pharmacological Features of Vascular Responses of Isolated Dog and Monkey Lingual Arteries to Vasoactive Substances

Pharmacological Features of Vascular Responses of Isolated Dog and Monkey Lingual Arteries to Vasoactive Substances

Characteristics of the Responses of Isolated and Perfused Canine Splenic Arteries to Vasoactive Substances and to Periarterially Electrical Stimulation

Demonstration of .ALPHA.1-adrenoceptors in human hypertrophied prostate with tritiated bunazosin.

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