Antihypertensive effect of combined treatment with .ALPHA.- and .BETA.-adrenergic blockers in the spontaneously hypertensive rat.

Igarashi, Toshiji; Nakajiama, Yoshikage; Ohtake, SHlNZABURO

doi:10.1253/jcj.41.903

Cited by 30 publications

(7 citation statements)

References 7 publications

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“…significantly inhibited high blood pressure and heart rate in SHR. In general, 30 mg/kg of oral propranolol does not reduce elevated blood pressure (17), but 100 mg/kg of oral propranolol reduced elevated blood pressure significantly (18). These results suggest that relatively low doses of oral propranolol can reduce the rise in blood pressure if the treat ment is begun at an early stage of hyper tension.…”

Section: Discussionmentioning

confidence: 99%

Hemodynamics and monoamine oxidase activity in spontaneously hypertensive rats (SHR)

et al. 1983

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Abstract-The relationship between the onset of hypertension and changes in monoamine oxidase (MAO) activity in the brains and hearts of spontaneously hypertensive rats (SHR) were studied. After 7-weeks-old, blood pressure of SHR increased rapidly and reached a level of 170 to 180 mmHg; but following 4 weeks of propranolol treatment (10 mg/kg/day), blood pressure decreased significantly compared to that of untreated SHR. Heart/body weights ratio of SHR was higher than that of normotensive Wistar Kyoto rats (WKY). MAO activities in the brain stem, the medulla oblongata and pons of the SHR were significantly higher than those in WKY at 7 weeks of age, and MAO activity in the brain stem of the propranolol-treated SHR was significantly lower than that in the untreated SHR. Propranolol inhibited MAO activity in brain tissue in vitro, and the 150 values of propranolol were identical (1 X10-4 M) in SHR and WKY. In both the WKY strain and the SHR, the Vmax values of heart MAO increased with age, and the Vmax values of SHR were twice those of WKY. Km values for tyramine of heart MAO in WKY and SHR were approx. 100 PM and 140 ,iM, respectively; however, these values were not age-dependent. It was concluded that an increase in MAO activity in SHR brain stem may trigger a reduction in noradrenaline content and that propranolol may be responsible for its restoration, thus reducing peripheral sympathetic activity; moreover, the increase in MAO activity in the hearts of SHR may be of genetic origin.

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Section: Discussionmentioning

confidence: 99%

Hemodynamics and monoamine oxidase activity in spontaneously hypertensive rats (SHR)

et al. 1983

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“…This reaction may be attributable to the peripheral vasodilative effect of bunazosin, which is a selective α 1 -adrenergic antagonist. 22 Bunazosin had to be discontinued in three of the four patients who developed conjunctival hyperemia, indicating the need for monitoring for conjunctival hyperemia in patients using this drug.…”

Section: Discussionmentioning

confidence: 99%

Addition of or Switch to Topical Bunazosin Hydrochloride in Elderly Patients with Normal-Tension Glaucoma: A One-Year Follow-up Study

Yoshikawa

Katsushima²,

Kimura

et al. 2006

Jpn J Ophthalmol

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“…In unanesthetized normotensive rats, bunazosin by oral administration did not affect systemic blood pressure (3,4,8). However KB post/KB pre was used as an index of the relative selectivity of the antagonists on the presynaptic aadrenoceptors.…”

Section: Cardiovascular Effectsmentioning

confidence: 99%

“…pertensive rats (3,4) and stroke-prone spontaneously hypertensive rats (8,9), intravenous bunazosin produced an immediate fall in systolic blood pressure and oral bunazosin prevented a progressive development of hypertension over a 4-week period. These results suggested that bunazosin has antihypertensive activity in these hypertensive models.…”

Section: Cardiovascular Effectsmentioning

confidence: 99%

Bunazosin

Sakanashi¹

1988

Cardiovascular Drug Reviews

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Bunazosin (E-643) is a quinazoline derivative with a ,-adrenoceptor blocking activity, which was recently developed in Japan. Its chemical name is 4-amino-2-(4-butyrylhexahydro-1H-1,4-diazepin-1 -y1)-6,7-dimethyoxy-quinazoline hydrochloride (Fig. 1). The synthesis of bunazosin was previously described by Yamato et al. (17) (Fig. 2).Bunazosin is a white crystalline powder. It is insoluble in chloroform, ethanol, and n-butanol; poorly soluble in water and methanol; and well soluble in formic acid. Bunazosin is essentially not sensitive to light, temperature, or moisture. At room temperature and room light, bunazosin is stable for at least 3 years. PHARMACOLOGICAL STUDIESMechanism and Sites of Action Shoji (1 3) compared bunazosin and four other a-antagonists for their ability to block pre-and postsynaptic a-adrenoceptors in the isolated rat vas deferens. He found the following order of affinity for presynaptic a-adrenoceptors: phentolamine > yohimbine > tolazoline > bunazosin 2 prazosin; and for postsynaptic a-adrenoceptors: bunazosin 2 prazosin > phentolamine > yohimbine > tolazoline. He assessed selectivity for presynaptic versus postsynaptic a-adrenoceptors by comparing KB values (Table l), and concluded that bunazosin is a potent and highly selective postsynaptic a ,-adrenoceptor antagonist.Using 3H-radiolabeled bunazosin, Hata et al.(1) showed that [3H]bunazosin binds specifically to rat brain preparation with a B,,, value of 84.6 k 8.4 fmol/mg protein and a Kd value of 0.59 k 0.04 nM. Prazosin markedly inhibited [3H]bunazosin binding to the rat brain preparation, while yohimbine and clonidine had only a slight effect ( Table 2). Binding of [3H]bunazosin to tissues other than brain is shown in Address correspondence and reprint requests to Dr. M. Sakanashi

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Antihypertensive effect of combined treatment with .ALPHA.- and .BETA.-adrenergic blockers in the spontaneously hypertensive rat.

Cited by 30 publications

References 7 publications

Hemodynamics and monoamine oxidase activity in spontaneously hypertensive rats (SHR)

Hemodynamics and monoamine oxidase activity in spontaneously hypertensive rats (SHR)

Addition of or Switch to Topical Bunazosin Hydrochloride in Elderly Patients with Normal-Tension Glaucoma: A One-Year Follow-up Study

Bunazosin

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