Ventilatory Response to CO2 Rebreathing After Adrenergic Blockade in Goats

Administration of adrenergic agonists enhances resting ventilation and increases responsiveness to C02 inhalation, though there are conflicting data about the effect of adrenergic blockade on ventilatory responses. In this study, we investigated the effect of alpha- or beta-adrenergic blockade on th...

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Bibliographic Details
Main Authors: Weinberger,Steven E, Gabel,Ronald A, Steinbrook,Richard A, Leith,David E, Harris,Richard
Format: Report
Language:English
Subjects:
ASS10
CARBON DIOXIDE
DOSAGE
EPINEPHRINE
EXPERIMENTAL DATA
GOATS
HEART RATE
HYPOXIA
INHALATION
ISOPROTERENOL
NERVE BLOCKING
PE61102A
PHARMACOLOGICAL ANTAGONISTS
Pharmacology
Phentolamine
Propranolol
RESPIRATION
RESPONSE(BIOLOGY)
VENTILATION
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Summary:Administration of adrenergic agonists enhances resting ventilation and increases responsiveness to C02 inhalation, though there are conflicting data about the effect of adrenergic blockade on ventilatory responses. In this study, we investigated the effect of alpha- or beta-adrenergic blockade on the ventilatory response to hyperoxic C02 rebreathing in awake goats. Five goats were studied before and after intravenous administration of phentolamine (3.8 mg bolus followed by 0.19 mg/min) or propranolol (0.15 mg/kg). Adequacy of alpha- or beta-adrenergc blockade was subsequently demonstrated by assessing the pressor response to norepinephrine or the heart rate response to isoproterenol, respectively. There was no difference (compared to control studies) in the mean slope, x-intercept, or ventilation at end-tidal PC02 = 70 torr for the C02 response curves after the goats had received either phentolamine or propranolol. When mean inspiratory flow rate (VT/Ti) was plotted against end-tidal PCO2, there was also no change in slope x-intercept or VT/Ti at end-tidal PCO2 = 70 torr after the goats had received propranolol.