A Phosphorescence Quenching Study Ross D. Shonat and Paul C. Johnson. Department of Physiology, University of Arizona, Tucson, AZ 85724. The results support the hypothesis that oxygen can diffuse across the walls of postcapillary vessels and suggest that the venular structures are not merely passive conduits for removing oxygen and waste products but may play an important role in regulating oxygen delivery. Schematic of a typical region selected for study, showing a segment of venular tree structure and associated arcade vessels. Site 9 is a postcapillary venule, and site 5 is the junction of a 3rd order venule and arcade venule.
Arrows indicate flow direction and muscle fiber orientation.
Blunt-ended vessel segments within venular tree structure drain other regions of tissue not drawn in this schematic. Small arterioles running parallel to tree structure venules are not typically found in this preparation. X-Y coordinate of each site is known and is used to calculate absolute distances and allow for stage positioning. Data are expressed as a function of position only in the venular tree structure, with origin defined as 3rd order venular junction vessel. Each animal is represented by a different symbol outline, with fill color or pattern of a given symbol defining a different region in a given animal.