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EFFECTS OF A CONTINUOUS INFUSION OF DOPAMINE ON THE VENTILATORY AND CAROTID BODY RESPONSES TO HYPOXIA IN CATS
Author(s) -
Ide Tohru,
Shirahata Machiko,
Chou ChungLong,
Fitzgerald Robert S.
Publication year - 1995
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1995.tb02084.x
Subject(s) - carotid body , cats , hypoxia (environmental) , hypoxic ventilatory response , dopamine , anesthesia , medicine , cardiology , chemistry , respiratory system , carotid arteries , oxygen , organic chemistry
SUMMARY 1. We investigated how a continuous infusion of dopamine (DA; 5μg/kg per min), which is often used clinically, would affect the ventilation and carotid chemoreceptor neural activity in anaesthetized cats. 2. In anaesthetized, spontaneously breathing cats, tidal volume (Vt) and respiratory frequency (f) were continuously monitored at five levels of inspired oxygen (P10 2 = 110,130, 150, 170, 760mmHg) during Da or saline infusion. Vt and f were sampled for 1 min after 3 min exposure to each level of P10 2 . Time control study was also performed. 3. DA infusion significantly lowered V T under both normoxia and hypoxia in seven of eight cats. Respiratory frequency was not affected by DA infusion. Depression of ventilation during post‐hypoxic hyperoxia was augmented by DA infusion. Chemodenervntion abolished the ventilatory response to hypoxia and DA did not further affect the ventilatory response to hypoxia. 4. In a second group of artificially ventilated cats, carotid chemoreceptor neural activity was recorded at five levels of arterial oxygen tension. DA infusion significantly depressed carotid chemoreceptor neural activity during normoxia and hypoxia in six of seven cats. 5. These findings suggest that changes in ventilation during low dosage of DA infusion closely correlate with carotid body neural output. A predominant effect of this dosage of DA (5 μg/kg per min) was depression in the ventilatory response to hypoxia due to an inhibition of carotid body neural output.