Cardiovascular effects of the alpha2-adrenergic receptor agonist medetomidine in clinically normal cats anesthetized with isoflurane.
OBJECTIVE
To assess the cardiovascular effects of the alpha2-adrenergic receptor agonist medetomidine in healthy cats anesthetized with 2% isoflurane.


METHODS
11 clinically normal cats.


METHODS
Cats were anesthetized with isoflurane, and catheters were inserted for measurement of aortic, left ventricular, and right atrial pressures. For data collection, end-tidal isoflurane concentration was reduced to 2%, and end-tidal CO2 was maintained at 35 to 40 mm of Hg by use of positive-pressure ventilation. After measurement of baseline data, medetomidine (0.01 mg/kg of body weight, i.m.) was administered and data were collected continuously for 75 minutes. At the end of data collection, incisions were closed and cats were allowed to recover from anesthesia.


RESULTS
Medetomidine significantly increased mean arterial pressure and systemic vascular resistance. The increase in mean arterial pressure was maximal at 17.8 +/- 7 minutes after medetomidine administration. Medetomidine also increased left ventricular peak systolic pressure, left ventricular end diastolic pressure, and right atrial pressure. Medetomidine significantly decreased heart rate and mean aortic flow.


CONCLUSIONS
The low dosage of medetomidine (0.01 mg/kg, i.m.) promoted severe vasoconstriction in isoflurane-anesthetized cats, and resulted in sustained increases in left ventricular preload and afterload.
Golden
A L
AL
Department of Biological Sciences, Kennesaw State University, GA 30144-5591, USA.
Bright
J M
JM
Daniel
G B
GB
Fefee
D
D
Schmidt
D
D
Harvey
R C
RC
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000769:Anesthesia, Inhalation; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002415:Cats; D004562:Electrocardiography / Q000187:drug effects; D005260:Female; D006439:Hemodynamics / Q000187:drug effects* / Q000502:physiology; D007093:Imidazoles / Q000494:pharmacology*; D007530:Isoflurane; D008297:Male; D020926:Medetomidine; D018341:Receptors, Adrenergic, alpha-2 / Q000502:physiology*; D013997:Time Factors; D014655:Vascular Resistance / Q000187:drug effects; D016277:Ventricular Function, Left / Q000187:drug effects
D000316:Adrenergic alpha-Agonists; D007093:Imidazoles; D018341:Receptors, Adrenergic, alpha-2; D007530:Isoflurane; D020926:Medetomidine