Jeffery M. Morrissette

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This study reports the cardiovascular physiology of the Pacific bluefin tuna (Thunnus orientalis) in an in situ heart preparation. The performance of the Pacific bluefin tuna heart was examined at temperatures from 30 degrees C down to 2 degrees C. Heart rates ranged from 156 beats min(-1) at 30 degrees C to 13 beats min(-1) at 2 degrees C. Maximal stroke(More)
Tuna are endothermic fish with high metabolic rates, cardiac outputs and aerobic capacities. While tuna warm their skeletal muscle, viscera, brain and eyes, their hearts remain near ambient temperature, raising the possibility that cardiac performance may limit their thermal niches. We used an in situ perfused heart preparation to investigate the effects of(More)
Shark populations are declining globally, yet the movements and habitats of most species are unknown. We used a satellite tag attached to the dorsal fin to track salmon sharks (Lamna ditropis) for up to 3.2 years. Here we show that salmon sharks have a subarctic-to-subtropical niche, ranging from 2 degrees to 24 degrees C, and they spend winter periods in(More)
Bluefin tuna are endothermic and have higher temperatures, heart rates, and cardiac outputs than tropical tuna. We hypothesized that the increased cardiovascular capacity to deliver oxygen in bluefin may be associated with the evolution of higher metabolic rates. This study measured the oxygen consumption of juvenile Pacific bluefin Thunnus orientalis and(More)
Tunas have an extraordinary physiology including elevated metabolic rates and high cardiac performance. In some species, retention of metabolic heat warms the slow oxidative swimming muscles and visceral tissues. In all tunas, the heart functions at ambient temperature. Enhanced rates of calcium transport in tuna myocytes are associated with increased(More)
Landeira-Fernandez, Ana M., Jeffery M. Morrissette, Jason M. Blank, and Barbara A. Block. Temperature dependence of the Ca -ATPase (SERCA2) in the ventricles of tuna and mackerel. Am J Physiol Regul Integr Comp Physiol 286: R398–R404, 2004. First published November 6, 2003; 10.1152/ajpregu.00392.2003.—Recent physiological studies on the cardiovascular(More)
Pacific bluefin tuna inhabit a wide range of thermal environments across the Pacific ocean. To examine how metabolism varies across this thermal range, we studied the effect of ambient water temperature on metabolic rate of juvenile Pacific bluefin tuna, Thunnus thynnus, swimming in a swim tunnel. Rate of oxygen consumption (MO2) was measured at ambient(More)
Recent physiological studies on the cardiovascular performance of tunas suggest that the elevated heart rates of these fish may rely on increased use of intracellular sarcoplasmic reticulum (SR) Ca2+ stores. In this study, we compare the cellular cardiac performance in endothermic tunas (bluefin, albacore, yellowfin) and their ectothermic sister taxa(More)
In selectively isolated basolateral (bILPM) and canalicular (cLPM) rat liver plasma membrane vesicles, the in vitro effect of cyclosporine A (CsA) on specific hepatic membrane transport processes was examined. CsA (0.1-200 microM) caused a concentration-dependent inhibition of initial rates of Na(+)-dependent taurocholate uptake in bILPM and cLPM vesicles(More)
A thermogenic organ is found beneath the brain of billfishes (Istiophoridae), swordfish (Xiphiidae) and the butterfly mackerel (Scombridae). The heater organ has been shown to warm the brain and eyes up to 14 degrees C above ambient water temperature. Heater cells are derived from extraocular muscle fibers and express a modified muscle phenotype with an(More)