Vascular volume-distensibility characteristics of the isolated dogfish gut.

The vascular capacitance and volume distensibility of the isolated dogfish gut and segments of dogfish arteries and veins were investigated. The volume-distensibility curves for dogfish arteries and veins are very similar to comparable curves derived from arteries and veins of dogs or man. The vascular volume-distensibility curve of the gut, however, shows a greater distensibility at higher systemic pressure than at lower pressure. Evidence is presented that significant amounts of fluid leave the vascular compartment at a lower systemic pressure than in an isolated dog hindlimb preparation. However, this alone does not explain the atypical vascular volume-distensibility curve obtained from the dogfish gut. It is suggested that in the dogfish capillary filtration pore enlargement takes place at a very low capillary pressure or volume (compared to mammals) and this complicates the construction of a volume-distensibility curve because initial vascular volume is not constant.