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Fig. 6. The effect of L-NAME on internal contraction ratios. (A)
Contractions of the same demibranch in response to 2x10-5 mol
l-1 5HT (applied at the upward arrows). The response to each dose
of 5HT was terminated by flushing the organ bath (downward arrows).
L-NAME (10-4 mol l-1) was applied for 15 min
before the second contraction. The resulting internal contraction ratio was
0.92. (B) Various concentrations of L-NAME were applied to isolated
demibranchs for 15 min between their first and second contractions in response
to 2x10-5 mol l-1 5HT Values are means ± 1
S.E.M., N=3 for all concentrations of L-NAME
except 10-4 mol l-1 where N=4.