The APS Journal Legacy Content is the corpus of 100 years of historical scientific research from the American Physiological Society research journals. This package goes back to the first issue of each of the APS journals including the American Journal of Physiology, first published in 1898. The full text scanned images of the printed pages are easily searchable. Downloads quickly in PDF format.
Little is known about the time course and extent of the changes in radial arterial pressure and heart rate taking place in patients with arteriosclerosis obliterans during walking, as well their subtending mechanisms. For this reason the authors measured these variables in 23 patients with arteriosclerosis obliterans and in nine normal subjects (control group), during treadmill walking and several tests. In the patients a rapid and marked increase in radial arterial pressure was recorded during walking, whereas the same parameter either fell abruptly or persisted at elevated levels during recovery. This pattern markedly differed from that recorded in normal subjects, and it was mainly brought about by the activation of the exercise pressor reflex. The following findings suggested that the exercise pressor reflex was activated: the conditions required for activation of the reflex were present in our patients; the pressure changes observed during walking tightly paralleled the changes due to this reflex activation; the hypertensive response to walking was enhanced by increases in severity of disease and in walking speed and duration; the reflex activity persisted during recovery; and the pressure pattern during walking was reproduced by walking with arrested blood circulation to a lower limb. On the contrary, the behavior of heart rate was similar in patients and normal subjects both during walking and recovery because it was not influenced by the exercise pressor reflex.
The APS Journal Legacy Content is the corpus of 100 years of historical scientific research from the American Physiological Society research journals. This package goes back to the first issue of each of the APS journals including the American Journal of Physiology, first published in 1898. The full text scanned images of the printed pages are easily searchable. Downloads quickly in PDF format.
We have investigated the influence of changes of perfusion pressure and local peripheral resistance on blood flow velocity waveform and profile in normal human peripheral arteries. Blood flow velocity and profile were recorded from the distal end of the left brachial artery in ten normal subjects by means of an ultrasonic device. The records were obtained in basal conditions and after blood pressure in the brachial artery and local peripheral vascular resistance were changed, separately or together, by progressive inflation of two arm cuffs, one encircling the proximal half of the left arm and the other the middle part of the left forearm. Both blood flow velocity waveform and profile were shown to be markedly modified by changes in perfusion pressure and local peripheral vascular resistance. Reduction of perfusion pressure decreased both forward and reverse peak velocities, but had the largest effect upon reverse velocity. The upslope and the downslope of the forward velocity wave were left unchanged. Increase in local peripheral vascular resistance markedly augmented reverse peak velocity, whether perfusion pressure was normal or reduced. Increased resistance only slightly influenced peak forward velocity.
Desynchronized sleep (DS) in the cat is accompanied by a long-lasting (tonic) constriction of muscle blood vessels (conductance decrease 5-30%), on which are superimposed short-lasting (phasic) vasoconstrictor waves that occur simultaneously with bursts of rapid eye movements and body twitches. Both the tonic and the phasic vasoconstrictions are abolished after regional sympathectomy (conductance increase 5-10%). Tonic vasoconstriction can also be prevented by hind-limb deafferentation (bilateral section of the dorsal roots from L5 down) or by transection of the spinal cord at L4 in such a way as to separate sympathetic innervation from afferent input from the hind limbs. These procedures do not affect the phasic vasoconstrictions. After lumbar sympathectomy or hind-limb deafferentation, iliac blood flow decreases during the tonic fall in blood pressure associated with DS by exactly the amount (1-2 ml/min) predicted by pressureflow relationships observed during artificial lowering of iliac blood pressure. We conclude that tonic and phasic vasoconstrictions are both due to sympathetic discharges. However, phasic sympathetic discharges are driven by central descending influences, and tonic sympathetic vasoconstriction depends on reflex influences originating from the limbs themselves. When tonic sympathetic vasoconstriction is prevented, muscle blood vessels exhibit autoregulatory behavior during DS.
KEY WORDS hind-limb deafferentation spinal vasomotor reflexes muscle afferent fibers tonic and phasic vasoconstriction iliac blood flow autoregulation
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