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Mammalian differences in baroreflex control of coronary conductance
Author(s) -
Quail Anthony,
Hamut Mutalip,
Seah Peng,
McLeod Damian,
Cottee David,
White Saxon
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.1034.6
Subject(s) - dilator , baroreflex , medicine , cardiology , heart rate , coronary circulation , anesthesia , blood pressure , blood flow
Integrated autonomic control of the coronary circulation is inconsistent with respect to vagal cholinoceptor activity. Baroreflex control of regional coronary conductance was investigated in chronically prepared awake sheep, and compared to our dog data. Pulsed Doppler flow probes were implanted on the right (R), circumflex (Cx) and anterior descending (AD) coronary arteries. Aortic (P a ) and central venous pressure catheters were placed via the superficial cervical vessels. Baroreflex responses were evoked by elevating upper‐body P a using an external aortic occluder at a controlled (atrioventricular pacing) heart rate (HR) of 150 and 180 min −1 . Pacing the heart upward raised baroreflex and metabolic activity and evoked a differential rise in coronary conductance where Cx was greatest followed by R then AD. Block of cholinoceptors (ch), β‐adrenoceptors (β), alone and together (ch‐β), then with α‐adrenoceptors (α) block, at different HR, revealed that in all 3 beds an underlying ch constrictor effect was balanced by the summed dilator effects of β, plus a probable α‐enhanced, vagal interaction mechanism. The net effects summate to enhance conductance in Cx, but balance in R and AD. Therefore, differences exist between species for baroreflex evoked cholinoceptor effects in the mammalian coronary circulation. These are constrictor in sheep, and dilator in the dog. Funding: Hunter Medical Research Institute