Adrian Cairns

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The excitability of A fibers of peripheral nerves in vitro is more susceptible to depression by energy lack than is excitability of C fibers. Whether there is also a differential vulnerability between small myelinated A delta fibers that conduct fast pain and large myelinated A beta fibers is unclear. We evaluated the relative abilities of A beta and A(More)
Differential block of peripheral nerve fibers was attempted in vitro by a new approach based on inhibiting the membrane pump with ouabain. Sequential concentration dependent extinction of the components of the compound action potential was obtained: C extinguished first, A delta next, A beta last. The sequence conforms to expectations based on axonal size.(More)
The neural activation of the diaphragm during quiet and vigorously stimulated breathing has been hypothesized to be submaximal. In this study, we measured phrenic motoneuron firing rates during brief progressively increasing inspiratory resistive loads in anesthetized rabbits. We recorded activity in 68 phrenic motoneurons in 17 rabbits. We found that 40 of(More)
The potential clinical scope of use-dependent block of conduction (UDB) was assessed by studying characteristics of UDB in vitro in individual mammalian axons. Single and repetitive stimulation was applied to rabbit cervical sympathetic and vagus nerves exposed to solutions containing lidocaine 0, 0.3, or 0.6 mmol/l (9.1 or 18.2 mg/dl) at 37 degrees C. Unit(More)
The differential susceptibility of large and small axons to lidocaine was studied on units in the rabbit vagus nerve. The results classified the units into three groups: 1) myelinated, conduction velocity 37.5-5 m/s, which were blocked by lidocaine 0.4-0.8 mM; 2) slow, unmyelinated axons, conduction velocity 1.2-0.5 m/s, and these axons were not blocked by(More)
The study of compound action potentials has not succeeded in determining exact limits to differential block of nerve fibers by local anesthetics. Further observations on individual neurons therefore were undertaken. Rabbit vagus nerve and ganglion were superfused in vitro at 37 degrees C, pH 7.4. Activity evoked by stimulating the distal end of the nerve(More)
Biphasic field potentials were recorded in the CA3 distal dendritic region in response to both antidromic (fornix) and orthodromic (mossy fiber) stimulation in guinea pig hippocampal slices in vitro. The positive component (P1) corresponded to intracellularly recorded excitatory postsynaptic potentials. The negative component (N1) appears to be due to(More)
The levels of noise necessary to effectively mask the stimuli commonly used in auditory brainstem response (ABR) tests were determined. The relative masking level (RLM) of twenty normally-hearing volunteers was measured behaviourally using ipsilaterally presented unfiltered noise in the presence of ABR stimuli. The upper limit for RLM was found to be(More)
Phrenic motoneuron firing rates during brief inspiratory resistive loading (IRL) are high, and nearly all the motoneurons are recruited. Diaphragmatic fatigue has been difficult to demonstrate during IRL. Furthermore, evidence from studies in limb muscles has shown variable motoneuron responses to prolonged high-intensity loads. We studied phrenic(More)