An ultrastructural study of intrarenal catecholamine-containing elements

Histochemical visualization of catecholamines and electron microscopy in the same tissue sample were used to localize and study catecholamine-containing nerve enlargements or swellings in male Wistar and Sprague-Dawley rat kidneys. These swellings lie in the perivascular nerve plexuses of arcuate and interlobular arteries near the points of origin of arterioles, and are composed of modified axons and associated Schwann cells. Transverse sections of the enlarged nerves reveal that individual axons are also enlarged, have processes or folds and make contact with one another. The axonal enlargements contain small mitochondria with a dense matrix and clusters of small vesicles, many of which are associated with an organelle composed of parallel cisternae of smooth membranes.     

Superposition of Excitatory and Inhibitory Influences in the Retina of Limulus: Effect of Delayed Inhibition

In an optic nerve fiber of the compound eye of the horseshoe crab, Limulus, the time course of a train of nerve impulses discharged in response to illumination reflects the interplay of excitatory and inhibitory influences. Responses to sinusoidally modulated excitation and inhibition, as a function of frequency, were measured separately and in combination. A simple linear superposition of the separate frequency responses properly accounts for the composite frequency response for both synchronous and asynchronous modulation of the excitatory and inhibitory influences. In general, the effect on the frequency response of increasing the delay of the inhibitory influence is progressively to shift the maximum amplitude to lower frequencies and gradually to produce pronounced maxima and minima in both the amplitude and phase.     

Quadriceps strengthening with the DAPRE technique: case studies with neurological implications

The Daily Adjustable Progressive Resistive Exercise (DAPRE) technique was developed clinically in an effort to provide an objective means of increasing resistance concurrently with strength increases during knee rehabilitation subsequent to injury/surgery. The key to the DAPRE technique is that on the third and fourth sets of exercise the patient performs as many repetitions as possible. The number of repetitions performed during the third and fourth sets is used to determine the amount of weight that is added to (or sometimes removed from) the working weight for the next set and session, respectively. Consequently, patients exercise nearer their optimal capacity during each weight rehabilitation session, and their strength redevelopment occurs at a much faster rate. This report describes the quariceps muscle strength gains by 21 athletes who used the DAPRE technique following knee immobilization for a minimum of 3 wk. These patients averaged an increase of 4.3 +/- 2.2 (SD) kg X d-1 for a period of 6.4 +/- 2.2 d, as measured by a six repetitions maximum test. It seems unlikely that morphological changes were responsible for these strength increases. It is postulated that strength redevelopment following immobilization involves changes in neural pathways and/or overcoming possible neural inhibitors.