Fig. 7. Changes in [Ca2+]i of rectal gland tubules (RGTs) in
response to calcium, spermine and gadolinium treatment. (A) The stimulatory
effect of spermine (N=7) on [Ca2+]i in RGT was
greater than that achieved by Gd3+ (N=10)
(*P<0.01 compared to baseline,
**P<0.01 for spermine versus calcium,
P<0.05 for Gd3+ versus
Ca2+). Values are means ± S.E.M. (B) Representative example
of the response of RGT in calcium-free shark Ringer to
[Ca2+]e followed by spermine. (C) Representative example
of RGT showing the stimulatory effect of sequential addition of external
Ca2+ and Gd3+ at the times indicated by the arrows.
