Portland State University. Department of Biology
Stanley S. Hillman
Term of Graduation
Date of Publication
Master of Science (M.S.) in Biology
Body fluids -- Regulation, Bufo marinus -- Physiology, Bullfrog -- Physiology
1 online resource (v, 102 pages)
The capillary filtration coefficient (CFC) and isovolumetric capillary pressure (Pci) were measured in Bufo marinus and Rana catesbeiana, using a gravimetric technique on an in vitro preparation while perfusing with Ringers and 0.1 g·100 ml-1 bovine serum albumin Estimates of pre- and post-capillary resistance were obtained from Bufo; the post- to pre-capillary resistance ratio was found to be 0.18, which was used to estimate capillary pressure. CFC was found to be 6.68 ± 0.51 and 5.07 ± 0.23 ml·min-1·kg-1·mmHg-1 and Pci was found to be 7.4 and 6.3 mmHg in Bufo marinus and Rana catesbeiana, respectively. An in vivo estimate of isovolumetric capillary pressure, after correcting for osmotic pressures of plasma proteins, would be approximately 11.5 and 9.3 mmHg for Bufo marinus and Rana catesbeiana, respectively. Using this resistance ratio, resting capillary pressures were estimated, based on published data, to be 10.8 and 11.3 mmHg for Bufo marinus and Rana catesbeiana, respectively. These results show that both of these anuran amphibians have a very high CFC, indicating a highly permeable capillary membrane, but they do not begin to filter until very high hydrostatic pressures are reached. Further, the differences between Bufo marinus and Rana catesbeiana indicate that the reversal of Starling forces from net filtration to net absorption during hypovolemia would occur sooner in Bufo than in Rana. This is consistent with the superior dehydration tolerance seen in toads versus frogs.
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Hancock, Thomas Vincent, "Whole Body In Vitro Hydraulic Conductivity and Transcapillary Filtration in Two Amphibians, Bufo marinus and Rana catesbeiana" (1997). Dissertations and Theses. Paper 5744.