Differential effects of nebivolol on adrenoceptors in the heart and in resistance arterioles in the rat. Quantitative intravital microscopic analysis
| Autor: | W. Loots, F. De Clerck |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Male
Time Factors Administration Topical Dopamine Video Recording Vasodilation Blood Pressure Pharmacology Nebivolol Pharmacology (medical) Angiotensin II Muscles General Medicine Arteries Adrenergic Agonists Propranolol Arterioles Ethanolamines Injections Intravenous medicine.symptom Intravital microscopy medicine.drug medicine.medical_specialty Adrenergic receptor Epinephrine Vasopressins Terbutaline Adrenergic beta-Antagonists Pharmacotherapy Phentolamine Internal medicine Isoprenaline medicine Animals Benzopyrans business.industry Rats Inbred Strains Differential effects Rats Endocrinology Vasoconstriction Vascular Resistance business |
| Zdroj: | European journal of pharmacology. 179(1-2) |
| ISSN: | 0014-2999 |
| Popis: | The effects of adrenoceptor antagonists on heart rate and on arteriolar reactions to epinephrine, terbutaline, vasopressin, angiotensin II or dopamine in the rat cremaster muscle were compared using ECG analysis and quantitative intravital microscopy. Phentolamine (0.5 mg/kg i.v.) significantly reduced the vasoconstriction of arterioles elicited by topically applied epinephrine (10(-8) to 3.3 x 10(-6) M) while propranolol (0.63 mg/kg i.v.) significantly attenuated the arteriolar vasodilatation elicited by topically applied terbutaline (10(-6) to 10(-4) M). Nebivolol (0.63 mg/kg i.v.) at a dose producing a reduction of resting heart rate equivalent to that caused by propranolol modified neither the epinephrine-induced constriction nor the terbutaline-induced vasodilatation of arterioles. The arteriolar vasoconstriction induced by topically applied vasopressin (9.3 x 10(-9) M), angiotensin II (9.4 x 10(-7) M) or dopamine (5.2 x 10(-5) M) was not modified by nebivolol either. While propranolol reduced the tachycardia and hypotension induced by isoprenaline (0.025, 0.1 microgram/kg i.v.), nebivolol reduced the cardiac rhythm increase but not the blood pressure drop in response to the catecholamine (0.025, 0.1, 0.4 micrograms/kg i.v.). The present intravital microscopic study in the rat demonstrated that, at a dose exerting cardiac beta 1-adrenoceptor blockade, nebivolol is devoid of significant activity on alpha 1-, alpha 2-, beta-2-adrenoceptors and on receptors for vasopressin, angiotensin II or dopamine in resistance arterioles. |
| Databáze: | OpenAIRE |
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