P3.17 Friday, Jan. 6 Experimental reduction of arterial oxygen content increases magnitude of postprandial cardiac hypertrophy in Burmese pythons (Python molurus) SLAY, CE*; ENOK, S; WANG, T; HICKS, JW; Univ. of California, Irvine; Aarhus University; Aarhus University; Univ. of California, Irvine firstname.lastname@example.org
The postprandial period in Burmese pythons (Python molurus) is marked by a large increase in oxygen consumption (up to 40-fold in animals fed 25% of their body mass) and significant hypertrophy of gastrointestinal organs. Previous experiments have described a rapid (within 48 hours) and pronounced (40%) postprandial ventricular enlargement, but recent work noted the absence of cardiac hypertrophy under a similar experimental protocol, and suggests postprandial cardiac hypertrophy be considered “facultative” rather than “obligatory.” We hypothesize that postprandial cardiac hypertrophy serves to augment cardiac output and oxygen delivery during a period of peak oxygen demand, and experimental reduction of arterial oxygen content should therefore stimulate more pronounced ventricular enlargement. In this study, we delivered meals equivalent to 25% of body mass to Burmese pythons and allowed them to digest under environmental normoxia, environmental hypoxia, or experimentally-induced anemia. While pythons digesting in normoxia exhibited no postprandial cardiac hypertrophy after 48 hours, animals digesting with reduced blood oxygen content exhibited a 14% increase in mass-specific ventricular mass. This work suggests that reduced blood oxygen content is a stimulant of postprandial cardiac hypertrophy. Under normoxic conditions, depletion of blood oxygen levels during digestion may be the “trigger” for cardiac hypertrophy; if this threshold is not reached, cardiac hypertrophy may not occur. CES would like to acknowledge support from the NSF GK-12 Fellowship (DGE-0638751 to UCI) and an NSF Graduate Research Fellowship. Additional funding was provided by NSF grant IOS 0922756 to JWH and by the Danish Research Council to TW.