ISSN:
1439-0426
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
The in vivo cardiovascular responses to hypoxia, and the intrinsic functional characteristics of the heart in vitro, were determined, and compared, in the Adriatic sturgeon (Acipenser naccarii). During exposure to hypoxia in vivo, blood oxygen content (Cao2) declined as water 02 partial pressure (Pwo2) was reduced, despite an increase in haematocrit. The main cardiovascular response was a reduction in dorsal aortic blood pressure, with a slight bradycardia, while cardiac output remained constant. Reduced oxygen content of the perfusate had significant inhibitory effects on the intrinsic performance of the heart in vitro, causing a reduction in the heart rate; a reduction in the sensitivity of responses to increased preload (Frank-Starling response), and a more rapid decline in power output and stroke volume when afterload was increased. Overall, the in vitro results suggest that hypoxia depresses the contractility of the heart (i.e. its inotropic responses). The reduction in dorsal aortic pressure in vivo may, therefore, counteract the depressive effects of hypoxia on heart contractility, and thereby avoid a hypoxic depression of cardiac output.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1439-0426.1999.tb00209.x
