The action of collagenase on skate electric organ has two distinct, but partially overlapping, phases: first, the dissociation of innervated electrocytes; and second, the denervation of individual electrocytes and the concomitant release of nerve terminals into the surrounding fluid (Fox et al., 1990).
The morphology of electrocytes after treatment of organs for 4 days at 6 [degrees] C is shown in Figures 4 and 5.
When salines from washed electrocytes are examined with Nomarski optics, free nerve terminals can be identified [ILLUSTRATION FOR FIGURE 6 OMITTED].
In view of the greatly extended periods of exposure to collagenase used in the present study, it was important to establish the basic electrophysiological properties of electrocytes so treated.
In the present study we show that skate electric organs dissociate into their component cellular elements (electrocytes, Schwann cells, nerves, and nerve terminals) when incubated in saline solutions containing 1% collagenase at temperatures down to 6 [degrees] C.
In both cases the tissue disruption techniques employed lead to the dissociation of presynaptic terminals from the innervated surface of the electrocytes. With Torpedo, these detached terminals can be bulk-isolated by conventional subcellular fractionation and are recoverable in synaptosome fractions: such preparations have been widely used for biochemical studies (see Dowdall and Zimmermann, 1977; Michaelson and Sokolovsky, 1978; Morel et al., 1977; and Zimmermann et al., 1979).
Bulk electrocyte preparations were produced by incubating whole electric organs in an equal volume of skate saline containing 1% (w/v) collagenase (Worthington CLS I) for up to 7 days at 6 [degrees] C.