. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. S. Figure 2. (A) Electrical activity of the heart muscle (upper trace) and contraction of the heart (lower trace) recorded simultaneously. Intra- cellular membrane potential was recorded from a muscle cell in the anterior region of the heart, and contraction at a site in the central region of the heart. (B) TTX has no effect on the muscle activity. Arrow head: Perfusing solution was changed from normal saline to saline containing TTX (10-*M). TTX arrests the beat of decapod crustacean hearts by suppressing neuronal spiki
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. S. Figure 2. (A) Electrical activity of the heart muscle (upper trace) and contraction of the heart (lower trace) recorded simultaneously. Intra- cellular membrane potential was recorded from a muscle cell in the anterior region of the heart, and contraction at a site in the central region of the heart. (B) TTX has no effect on the muscle activity. Arrow head: Perfusing solution was changed from normal saline to saline containing TTX (10-*M). TTX arrests the beat of decapod crustacean hearts by suppressing neuronal spiking in the cardiac ganglion (, Tazaki. 1971). However, the spontaneous slow potentials in the heart muscle of Triops were not affected by treat- ment with TTX at concentrations up to l(Th M (Fig. 2B). S\nchronous activity of the heart muscle cells Muscle activity was simultaneously recorded from two sites in the heart. Figure 3A shows two examples in which one recording site was near the anterior end (upper traces), and the other near the posterior end of the heart (lower traces). The periodic membrane potential changes were synchronized among the muscle cells within a time differ- ence of less than 50ms (Al, 16ms; A2, 12ms). Thus, the whole heart beat almost simultaneously. In the case shown in Figure 3A1. the slow potential recorded from the anterior region preceded that recorded from the posterior region. But in the case shown in Figure 3A2, the slow potential recorded from the posterior region preceded that recorded from the anterior region. No local region of the heart had activity that consistently preceded that of the rest of the organ. extends from the first to the twelfth thoracic segments and is suspended in the pericardia! cavity. The heart is to mm in length, but less than 1 mm in width in the preparations used. The heart tube bifurcates near its anterior end and opens at the head region just under the eyes; its posterior end is closed. The heart has 11 o
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
