Authors: Joseph Camacho Syed Aman Qadri Hongkun Wang Mary Kate Worden
Publish Date: 2006/09/07
Volume: 192, Issue: 12, Pages: 1327-1334
Abstract
The American lobster is a poikilotherm that inhabits a marine environment where temperature varies over a 25°C range and depends on the winds the tides and the seasons To determine how cardiac performance depends on the water temperature to which the lobsters are acclimated we measured lobster heart rates in vivo The upper limit for cardiac function in lobsters acclimated to 20°C is approximately 29°C 5°C warmer than that measured in lobsters acclimated to 4°C Warm acclimation also slows the lobster heart rate within the temperature range from 4 to 12°C Both effects are apparent after relatively short periods of warm acclimation 3–14 days However warm acclimation impairs cardiac function at cold temperatures following several hours exposure to frigid 5°C temperatures heart rates become slow and arrhythmic in warm acclimated but not cold acclimated lobsters Thus acclimation temperature determines the thermal limits for cardiac function at both extremes of the 25°C temperature range lobsters inhabit in the wild These observations suggest that regulation of cardiac thermal tolerance by the prevailing environmental temperature protects against the possibility of cardiac failure due to thermal stressThe authors are grateful to Jasmit Brar for experimental assistance and Brian Duling and Deforest Mellon for helpful discussions The experiments described here comply with the “Principles of animal care” publication No 86–23 revised 1985 of the National Institutes of Health and also with the current laws of the United States of America
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