. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 430 C. G. DUFORT ET AL lesioned animals showed a slow decrease in heart rate during the course of the salinity reduction, but the magni- tude of these rate decreases did not qualify them as a bradycardia under our criteria (Fig. 3). Interestingly, all of the lesioned lobsters exhibited reductions in ventilation rates during the course of the salinity reduction (Fig. 3). The salinity at which lesioned lobsters reduced their ventilation rates was not significantly different (P = , one-way ANOVA), from that of control or
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 430 C. G. DUFORT ET AL lesioned animals showed a slow decrease in heart rate during the course of the salinity reduction, but the magni- tude of these rate decreases did not qualify them as a bradycardia under our criteria (Fig. 3). Interestingly, all of the lesioned lobsters exhibited reductions in ventilation rates during the course of the salinity reduction (Fig. 3). The salinity at which lesioned lobsters reduced their ventilation rates was not significantly different (P = , one-way ANOVA), from that of control or sham-lesioned lobsters (control n = 3 [because scaphognathite records were poor in 2 of the 5 lobsters], ± ppt; lesion n = 5, ± ppt; sham-lesion n = 5, ± ppt), suggesting that the salinity response elements in the nervous system had been activated, but the lobsters were unable to modify their heart rates due to the lesions. Ion sensitivity Most (21 of 24) of the lobsters exposed to isotonic solutions lacking chloride showed a typical bradycardia response (Fig. 4). However, cardiac responses were seen in only 2 of 19 lobsters exposed to isotonic solutions lacking other ions, but containing chloride (Fig. 4). Statistically, the occurrence of a bradycardia was significantly dependent on the lack of chloride (Fig. 4). For example, lobsters did not exhibit bradycardia when exposed to an isotonic solution of choline chloride, but they did upon exposure to solutions of 100 -i n=7 oa OB C I < 80- 60- 40- 20- n=24 n=ll n=10 Seawater Na-free Solutions NaCl Cl-free Solutions Figure 4. Percentage of trials (n = 61) in which lobsters exhibited bradycardia responses when exposed to natural and artificial solutions containing various amounts of certain ions. Lobsters did not usually respond when exposed to solutions containing chloride, such as seawater (natural [« = 7, 32 ppt] and artificial (» = 4]). sodium-free solutions (choline chloride [n = 7] and sodi
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
