Increase in membrane excitability with 5HT in three different sized animals.

<p>(A) Counts of the number of action potentials during 500ms depolarizing pulses of varying current amplitudes in a representative pleural sensory neuron from an animal of approximately 100g. The slope of this relationship is a more sensitive indicator of changes in membrane excitability than measuring action potential threshold alone. The increase in excitability of the sensory neuron with 5HT can be measured from the change in the slope. (B) Sensory neurons isolated from an animal of three distinct sizes, small 78g, a larger animal 225g and a very small animal at 23g. A significant increase in excitability measured with the number of action potentials per nA of depolarizing current was observed at sensory neurons from all three animals (Comparing before and 5HT with a two-way ANOVA with Bonferroni post tests at all three animal weights, *P<0.05, **P<0.01). Data from sensory neurons from single animals in each group (n = 6 sensory neurons examined from each animal). A one-way ANOVA of the initial slopes (before) found no significant difference between the three animals.