ISSN:
1432-136X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary 1. Graded erythrocythemia was induced by isovolemic loading of packed red blood cells in the toad,Bufo marinus. Blood viscosity, hematocrit, hemoglobin concentration, maximal aortic blood flow rate and maximal rates of oxygen consumption were determined after each load. 2. Blood viscosity was related to hematocrit in the expected exponential manner; ln η=0.43+0.035 Hct (Fig. 2). 3. Maximal blood flow rates in the dorsal aorta were inversely proportional to blood viscosity and fit predictions of the Poiseuille-Hagen flow formula (Fig. 3). The effect of increased blood viscosity was to reduce aortic pulse volume, but not maximal heart rate (Figs. 4, 5). 4. Maximal systemic oxygen transport capacity (aortic blood flow rate x hemoglobin concentration x O2 binding capacity of hemoglobin) was linearly correlated with the maximal rate of oxygen consumption (Fig. 6). 5. These data indicate that optimal hematocrit theory is applicable for maximal blood flow rates in vivo, and that systemic oxygen transport is the primary limitation to aerial $$\dot V_{O_2 } $$ max in amphibians.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00694447
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