. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 182 M. S. GUIRGUIS AND J. L. WILKENS During walking, /H increased on average above controls (102 ± 2 min '). These animals showed no im- pairment in walking behavior. On the second or third day after the ligaments were cut, the heart chamber was reopened and the dorsal nerves were sectioned. After this procedure the compensatory increases seen in resting /H after ligament loss were re- versed (Fig. 4). During locomotion, /H increased slowly and steadily. The final rates after 25 min were significantly lower than those
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 182 M. S. GUIRGUIS AND J. L. WILKENS During walking, /H increased on average above controls (102 ± 2 min '). These animals showed no im- pairment in walking behavior. On the second or third day after the ligaments were cut, the heart chamber was reopened and the dorsal nerves were sectioned. After this procedure the compensatory increases seen in resting /H after ligament loss were re- versed (Fig. 4). During locomotion, /H increased slowly and steadily. The final rates after 25 min were significantly lower than those of control or ligament-loss animals. The rates were not significantly different from those observed during the same period in animals with only dorsal nerve loss (Fig. 2). These animals were reluctant to walk and continued to do so only if continuously prodded. Three ot the animals refused to walk longer than 21 min. The chelae often dragged along the belt, and after about 10 min of walking the animals seemed to be trying to recruit the chelae to aid walking. The abdomen also dragged. Responses of heart to uniinergic neurohormones When settled lobsters were injected with enough of each of the aminergic neurohormones to produce a circulating concentration of 1 n\f (assuming complete mixing), the result was significant and prolonged tachycardia (Fig. 5), whereas injection of the same volume of saline had no effect. DA caused the largest increase (83 ± 2 min"1), fol- lowed by 5-HT(79 ± 2 min"1) and OA (71 ± 3 min '). Heart rate remained elevated for more than an hour in almost all cases. The maximum /H values following injection of DA and 5-HT in denervated settled animals were similar to those 120 r 100 80 O 60 o ^ 40 20. Control Ligament loss and Denervation -10 10 20 Time (min) Figure 4. The compounded effects of alary ligament loss and de- nervation on the heart rate of exercising lobsters (n = 11 for control, same animals illustrated in Figs. 2 and 3; n = 5 for
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
