Showing papers in "Journal of Applied Physiology in 1969"

Measurement of regional cerebral blood flow with antipyrine-14C in awake cats.

Abstract: RmvIctx, MARTIN, JANE JEHLE, LOUIS SOKOLOFF, AND SEYMOUR s. KETY. Measurement of regional cerebral blood flow with antt$yrine-14C in awake cats. J. Appl. Physiol. 27(2): 296-300. 1969.-Antipyrine-14C was utilized for the quantitative measurement of regional cerebral blood flow in cats by means of an autoradiographic technique. The advantages of this technique over a previously described method are the uniformity of the brain-blood partition coefficient for antipyrine, the better resolution of the autoradiograms, the ability to make permanent 14C standards, the ability to obtain adjacent sections for histological studies, and the exposure of the autoradiograms at room temperature rather than a t -70 C. Errors in the determination of the tissue concentration of antipyrine-14C can arise from several sources. Those due to errors in replicate optical density measurements plus variations in section thickness were found to be 5.6%. The standards used introduced only a small error since the standard deviation of replicate standards was no greater than 1.1 %. Regional cerebral blood flow was measured in a series of six awake, unrestrained resting cats The values varied from 0.21 ml/g per min in the cerebral white matter to 1.74 ml/g per min in the inferior colliculus. Arterial Pco2 was 34 f 2.9 mm Hg, Po2 was 102 f 8.4 mm Hg, pH was 7.44 f .01, and hematocrit was 29 f 6.67,.

An underwater weighing system utilizing "force cube" transducers.

Abstract: AKERS, R., AND E. R. BUSKIRK. An underwater weighing system utilizing ’ ‘force cube” transducers. J. Appl. Physiol. 26(5) : 649-652. 1969.-An underwater weighing system is described in which four electronic force cubes are used for the measurement of underwater weight, and an open-circuit procedure for nitrogen washout from the lungs is used for the measurements of residual volume. The system is relatively compact, easy to use, and could be fabricated in most laboratory shops. An important advantage of the system is that the subject retains control of the submersion procedure which reduces his apprehension and promotes cooperation. Valid and reliable underwater weights can be obtained with the system. The average standard deviation among replicate determinations of body density in four subjects was 0.0015. The intraindividual range in density for these four subjects was 0.005. Subsequent routine utilization of the underwater weighing system has proven its reliability and practicality.

Mechanical components of human eye movements

Abstract: three lateral rectus muscles of three patients were measured while detached from the globe during strabismus surgery together with the force required to rotate the globe horizontally with both horizontal recti detached. The length-tension relationship was measured for several levels of innervation by requesting the patient to make known eye movements with the unoperated eye. Muscle tone in the primary position of gaze ranged from 12 to 17 g. The slope of the length-tension curve near the primary position was about 0.45 g/deg. The spring constant of the passive muscle components was about 0.25 and 0.33 g/deg for the globe suspensory tissues. This makes it possible to estimate the division of forces between agonist, antagonist, and suspensory tissues for any angle of gaze. The time course of isometric tension associated with saccades clearly reveals the pulsatile nature of net active state tension that accounts for the rapidity of saccadic e

Microscopy and viscometry of blood flowing under uniform shear rate (rheoscopy).

Abstract: Transparent cone and plate in a Wells-Brookfield LVT viscometer allow direct microscopic observation ( x 60–400 magnification) of blood flowing under specific rates of shear (0.6–1,380 set–1) while...