Activity of Abdominal Muscles Elicited From the Circulatory System

Abstract

The studies described in this paper deal with alterations in activity of abdominal inuscles and other slteletal inuscles which are elicited by changes in the cardiovascular system. A paper describing the initial studies was published in 1959 (45). Subsequent investigations have been described in Ph.D. theses by J. I<. Turner (94), L. D. Davis (as), D. I. Briggs (15), and A. S. Hoyc (57). Preliminary reports have been presented at meetings of the American Physiological Society and the American Heart Association (16, 30, 31, 44, 96, 99, 100). It seems appropriate to describe all of the studies in a single publication since they are concerned with the same basic problem, and the results are complementary in indicating that the activity of abdominal inuscles is increased selectively on a reflex basis when volume of blood in certain "low pressure" portions of the cardiovascular system, most probably thc left atrium, is reduced.

Developmental effects of selective breeding for an infantile trait: The rat pup ultrasonic isolation call

“…between USV production and thermoregulatory and/ or cardiovascular responses in the test situation (Blumberg & Alberts, 1990; and recently revised in Blumberg & Sokoloff, 1998). Following this hypothesis, differences in the levels of USV response at any age between selected lines could be secondary to differences created by selection acting directly on the development of brown adipose tissue thermogenesis or on the strength of an``abdominal compression reaction'' (Youmans et al, 1963) that could provide cardiovascular support for thermoregulation during cold exposure (Blumberg et al, 1999). If selection acted primarily on either of these physiological systems, we would expect to see differences between lines, either in the body temperature levels that pups maintained during the 15-to 30-min baseline period in the home cage nest and/or in the loss of temperature resulting from isolation testing.…”

Terrestrial locomotion does not constrain venous return in the American alligator,Alligator mississippiensis

“…Left ventricular stroke volume can also be reduced during inspiration in mammals (Charlier et al, 1974;Hoffman et al, 1965;Ruskin et al, 1973;Schrijen et al, 1975) due to a fall in effective ejection pressure of the left ventricle (Olsen et al, 1985). Contraction of the abdominal muscles during expiration aids venous return in mammals (Abel and Waldhausen, 1969;Youmans et al, 1963). In contrast to the inspiratory increase in IAP, intrathoracic and right atrial pressures decrease during inspiration in mammals, increasing blood flow in the veins located near the thorax, such as the jugular and hepatic veins and the superior vena cava (Abu-Yousef, 1992;Brecher and Hubay, 1955;Brecher and Mixter, 1953;Mixter, 1953;Moreno et al, 1967;Osada et al, 2002;Takata et al, 1992;Teichgraber et al, 1997;Willeput et al, 1984).…”

Maintenance of arterial pressure in infant rats during moderate and extreme thermal challenge

“…In addition to a chronic mechanism for maintaining arterial pressure, an acute pressor mechanism is suggested by the transient increases in MAP observed during extreme cooling (Figures 2 and 3). These pressor responses may be the result of the abdominal compression reaction (ACR; Youmans et al, 1963;Youmans, Tijoe, & Tong, 1974), a maneuver that improves venous return during periods of decreased cardiac output and venous pooling. The ACR entails compression of the abdominal muscles during expiration, resulting in increased intraabdominal and intrathoracic pressures.…”