Sequential changes in regional distribution of blood in Eptesicus fuscus (big brown bat) daring arousal from hibernation

Abstract

Heart rates were studied in deeply hibernating and in arousing bats (Eptesicus fuscus). Values range from an average of 12 beats/min in deep hibernation to an average of 800 beats/min during peak arousal.Body temperatures were recorded. Arousing bats develop the "usual" anteroposterior temperature gradient.The distribution of blood was determined (Sapirstein method), and capillary organ blood-flow rates were approximated in deeply hibernating, in arousing, and in postarousal bats.The study indicates that, after the initiation of arousal, there is a redistribution of blood such that capillary blood-flow rates in organs of the anterior body rise more rapidly than do those in organs of the posterior body. A higher metabolic requirement for oxygen by brown adipose tissue as compared to other tissues, and the relatively high rate of heat production by brown fat, are thought to be largely responsible for this "shunting" of blood to anterior body regions during early arousal.

Sodium pentobarbital induced alterations in regional distribution of blood in Peromyscus maniculatus (deer mouse) and Eptesicus fuscus (big brown bat)

“…Big brown bats spend extended periods of time in a torpid state during which urine production is at a minimum, and shunting of blood into wings at the expense of the kidney probably occurs during fli9ht. It is, therefore, feasible that the comparatively low value obtained in this and in previous studies (Rauch 1973;Rauch and Beafty 1975) reflects peculiarities in renal function characteristic of the bat. Renal function tests in this species should yield interesting results.…”

“…The cannula assembly for isotope injection, method for obtaining heart rate, organ and tissue weights, and assay for radioactivity were similar to a previous investigation (Rauch 1973).…”

“…Bats collected near Edmonton (53"301 N ; 113'45' W) and the Sierra Nevada mountains (about 37" N; 120" W) were kept as previously described (Rauch 1973).…”

“…The method used has been outlined in detail (Rauch 1973); it was similar to that for mice except for using the interfemoral vein as the isotope injection site.…”

“…Eptesicus fuscus from various regions of North America appear to be physiologically similar (Rauch and Beatty 1975;Rauch 1973) and since no marked differences occurred in blood distribution in similarly treated bats it has been considered valid to pool data of bats from the two geographically remote areas.…”