ISSN:
1432-1912
Keywords:
Circulation
;
dp/dt max
;
Cats
;
β-Adrenergic Blocking Drugs
;
Isoproterenol Antagonism
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary In closed-chest cats, anaesthetized with pentobarbital, a comparative study was carried out of the cardiovascular actions of fourβ-receptor blocking agents [propanolol, practolol,d(-) INPEA and LB 46] as well as of their antagonism to the effects of isoproterenol. Theβ-receptor blocking agents were injected intravenously in increasing doses until the positive inotropic action of isoproterenol was abolished. Changes in maximum rate of rise of ventricular pressure (dp/dt max) were taken as a measure of the inotropic action. Heart rate, enddiastolic ventricular pressure, ventricular pressure, arterial pressure and ECG were recorded. The following results were obtained: 1. Propranolol and practolol decreaseddp/dt max to a greater extent than did INPEA, whereas LB 46 in small doses was without effect and at larger doses caused an increase indp/dt max. 2. Propranolol caused a more pronounced decrease in heart rate than did practol or INPEA. Small doses of LB 46 decreased the heart rate, but this decrease was not further enhanced by increasing the dose. 3. Propranolol, practolol and INPEA decreased systolic and diastolic pressure more markedly than did LB 46. 4. The hypotensive action of isoproterenol was antagonized by propranolol, LB 46 or INPEA to a greater extent than its inotropic action; practolol however, had no influence upon the hypotensive action of isoproterenol. 5. The enddiastolic ventricular pressure was not affected by theβ-adrenergic blocking agents, but was significantly enhanced by a subsequent injection of noradrenaline.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00997301
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