Figure 4. Strychnine and phrenic nerve activity in situ.

A, recording of Phr nerve activity in the presence of 0.2 μm strychnine. At this concentration, phase durations and frequency were similar in the two populations. B, strychnine decreased the duration of inspiration (left) to a similar degree in the two populations, but decreased expiratory duration only in ethanol-exposed animals (right). C, post-inspiratory time was reduced to a similar degree in the two populations (left), whereas the second expiratory phase was reduced only in ethanol-exposed animals (right). D, Phr frequency was increased in both populations, but at a lower dose for the control group (left) and burst amplitude was not affected up to a concentration of 0.5 μm strychnine in both populations. Data for B–D are expressed as means ±s.e.m.ⁱP = 0.05, *P < 0.05, **P < 0.01, ***P < 0.001 as compared to baseline values before strychnine. #P < 0.05 and ##P < 0.01, between populations.