Reactivity of Aorta and Portal Vein in Germfree Rats

Abstract

The responsiveness of conventional and germfree rat aortas and portal veins to vasoactive agents were compared in vitro. The results indicate: (1) aortas and portal veins from germfree rats exhibit an attenuated reactivity to angiotensin, vasopressin and epinephrine but not to KC1; (2) the dose-response curves for epi-nephrine and the peptides were shifted to the right concomitant with a decrease in maximum contractile tension, and (3) CaCl₂ dose-response curves obtained on potassium-depolarized aorta were not different from one another, whereas those obtained on portal veins from germfree animals were shifted to the right with a concomitant decrease in maximum response. In addition, aortas and portal veins from germfree rats were found to exhibit a higher total Ca content (but not Mg or water) when compared to conventional animals.

Gnotobiotics and the Microbiome

“…Other metabolic parameters that tend to be higher or greater in GF animals as compared to CV animals include pH of cecal contents (Thompson and Trexler, 1971), mean intracolonic oxygen pressure (Bornside et al, 1976), pulmonary arteriovenous oxygen values (Schwartz, 1975), plasma levels of some steroids (Einarsson et al, 1973), urinary citrate excretion (Gustafsson, 1948), and fasting blood glucose (Pleasants, 1974). In addition, aortas and portal veins have a higher total calcium content in GF animals (Altura et al, 1975), and the microvasculature is refractory to catecholamines (Gordon et al, 1966;Baez and Gordon, 1971).…”

“…This undoubtedly results from reduced (one-third normal) cardiac output and oxygen consumption (Wostmann et al, 1968), reduced regional blood flow and distribution (Gordon et al, 1966), decreased heart weight (Gordon et al, 1966;Albrecht and Souhrada, 1971), decreased total blood volume (Bruckner, 1997), and decreased pulmonary partial pressure of carbon dioxide values (Schwartz, 1975). Aortas and portal veins of GF rats have an attenuated reactivity to angiotensin, vasopressin, and epinephrine (Altura et al, 1975). Production of short-chain fatty acids are related to microbial activity (Håverstad and Midtvedt, 1986) and reduction of total body fats has been reported (Reina-Guerra et al, 1969).…”

“…Intrauterine infection represents a potential hazard to the axenic integrity of GF rats (Asano, 1969;Altura et al, 1975), since vertical transplacental transmission of Kilham rat virus (rodent Protoparvovirus 1) (Kajiwara et al, 1996;Jacoby et al, 2001) has been noted but, unlike mice (Kajima and Pollard, 1965), leukemia and mammary tumor viruses have not been observed in GF Fischer, Wistar, and Sprague-Dawley rat strains examined (Pollard and Kajima, 1966). The confirmation of encephalitozoan in GF rabbits (Hunt et al, 1972) suggests the likelihood of such vertical transmission possibilities in rats and other species.…”