Meeting Abstract

P3.18  Friday, Jan. 6  Cardiac performance across temperature extremes in the grass shrimp, Palaemonetes pugio. MIKA, Teresa L.*; REIBER, Carl L.; University of Nevada, Las Vegas; University of Nevada, Las Vegas

Metabolic rate increases in poikilothermic animals exposed to increased temperature.  The systems responsible for oxygen uptake and distribution must keep pace with this increased rate if these animals are to maintain aerobic metabolism. Analyses were performed on grass shrimp, Palaemonetes pugio, acclimated to 20° C exposed to a range of temperatures (5° – 40° C) in both normoxic and hyperoxic environments to determine response of the oxygen delivery system to this increased demand.  Animals placed in a hyperoxic environment had a higher CTmax than animals in a normoxic environment, suggesting a physical limitation in oxygen delivery. Previous work has indicated a limitation in diastolic filling time may be a main contributor to this limitation in oxygen delivery. Current work investigates the time in cardiac cycle across the range of temperatures to determine if this previously noted relationship is maintained across a wider range of heart rates. Pressure-area loops are also generated to provide an estimate of cardiac work and myocardial oxygen consumption in both normoxic and hyperoxic conditions.