Coronary hemodynamics during positive (+G-z) acceleration.
Left circumflex (LC) and left anterior descending (LAD) coronary flows, coronary perfusion pressure (P-ca), and arterial O-2 content (Cao-2) were determined in five dogs, lightly anesthetized with chloralose, during exposures to +2.0 and +3.0 G-Z stress; and for three of these dogs at +3.5-G-Z. At +2.0 G-Z, except for one dog with the most marked decrease in P-ca, KC and LAD flows increased above control by 15 s and thereafter gradually returned toward control; coronary resistances were significantly below control at 15 and 30 s (p smaller then 0.05). At +3.0 G-Z, LC and LAD flows were significantly greater than control (p smaller 0.05) from 30 to 60 s, while resistances were below control (p smaller than 0.05). At +3.5 G-Z, LC flow was maintained above control by a much reduced resistance, with P-ca below control; LAD flow increased in one dog, remained unchanged in one, and decreased slightly in one, although resistance always decreased. Cao-2 did not change significantly at any +G-Z level, and myocardial O-2 transport paralleled the changes in coronary flow.
D000054:Acceleration; D000337:Aerospace Medicine; D000818:Animals; D001693:Biological Transport, Active; D003326:Coronary Circulation; D004285:Dogs; D004780:Environment, Controlled; D006112:Gravitation; D006439:Hemodynamics; D009206:Myocardium / Q000378:metabolism; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption; D010477:Perfusion; D011312:Pressure; D013312:Stress, Physiological / Q000378:metabolism / Q000503:physiopathology; D014655:Vascular Resistance
D010100:Oxygen