Effects of brief starvation on muscle amino acid metabolism in nonobese man

A reduction in the release of substrate amino acids from skeletal muscle largely explains the decrease in gluconeogenesis characterizing prolonged starvation. Brief starvation is associated with an increase in gluconeogenesis, suggesting increased release of amino acids from muscle. In the present studies, accelerated amino acid release from skeletal muscle induced by brief starvation was sought to account for the accompanying augmentation of gluconeogenesis. To do this amino acid balance across forearm muscles was quantified in 15 postabsorptive (overnight fasted) subjects and in 7 subjects fasted for 60 h. Fasting significantly reduced basal insulin (11.3-7.5 muU/ml) and increased glucagon (116-134 pg/ml). Muscle release of the principal glycogenic amino acids increased. Alanine release increased 59.4%. The increase in release for all amino acids averaged 69.4% and was statistically significant for threonine, serine, glycine, alanine, alpha-aminobutyrate, methionine, tyrosine, and lysine. Thus, with brief starvation, muscle release of glycogenic amino acids increases strikingly. This contrasts with the reduction of amino acid release characterizing prolonged starvation. The adaptation of peripheral tissue metabolism to brief starvation is best explained by the decrease in insulin.

Ophthalmic arterial blood pressures measured by ocular plethysmodynamography

The indirect measurement of ophthalmic arterial blood pressure is an important index in the understanding of cerebral vacsular hemodynamics. Ophthalmodynamometry (ODM), the prototype for such measurement, is, however, replete with difficulties that have limited its widespread use. A preliminary evaluation of a new technique for ODM identified as ocular plethysmodynamography, has yielded accurate opthalmic blood pressure data without the attendant problems. Reproducible values for bilateral ophthalmic arterial pressure levels have been determined in 30 normal volunteers and the levels correlated to brachial arterial pressure levels. In a series of patients with arteriographically demonstrable carotid obstructive lesions, the preoperative and postoperative ophthalmic arterial blood pressure relationships exhibited excellent correlation with the roentgenographic and intraoperative data.

Assessment of arterial obstruction in vessels supplying the fingers by measurement of local blood pressures and the skin temperature response test--correlation with angiographic evidence

The systolic blood pressure measured in the fingers and wrists by the spectroscopic method and in the arm by auscultation were correlated with angiographic evidence of organic arterial obstruction in 29 patients. The pressures also were measured in 14 normal people. Results in the normal people suggest that a difference of more than 15 mm. Hg between the pressure measured simultaneously in corresponding fingers (or any two or more fingers), an absolute digital pressure less than 70 mm. Hg, or wrist-to-digit gradient of more than 30 mm. Hg, all in the warm subject and warmed hand, indicated the presence of organic obstruction. These criteria indicated the presence of organic arterial obstructive disease in 25 of 26 hands with definite angiographic evidence of it. The pressures were "normal" in five hands with no angiographic evidence of organic arterial obstruction. The digital skin temperature response to indirect heating was much less successful than were pressure measurements in identifying fingers with organic arterial obstructive disease.

Effect of physical exercise on internal carotid artery blood flow after arterial reconstruction

The effect of physical exercise on internal carotid artery (ICA) blood flow in conscious man was studied with the aid of electromagnetic flowmetry. A flow probe was implanted on the ICA in 25 patients after reconstruction of the artery. ICA mean blood flow and brachial artery mean blood pressure were continuously monitored in supine (25 patients) and sitting (24 patients) position at rest, during 5-6 minutes exercise on a bicycle ergometer and at rest after exercise. Arterial carbon dioxide tension (PaCO2) was studied in 6/25 work tests in supine and 7/24 in sitting position. Cardiac output was measured at rest and during exercise in 10/25 patients in supine and 8/24 patients in sitting position. In the supine group, ICA flow increased significantly within 1 minute and reached a maximal flow 15% above control flow within 2 minutes after the onset of exercise. The ICA flow then gradually declined, but remained almost significantly elevated, 7.5% above control, on termination of exercise. At rest, after exercise, the ICA flow decreased almost significantly to a level of 5% below the control flow within 5 minutes. There was a significant PaCO2 increase of 2.6 mmHg during exercise and a highly significant increase (72%) in cardiac output during exercise. The ICA flow at rest, before exercise, was about 15% lower in the sitting group than in the supine group. It increased in average 11.5% with 2 minutes of exercise and then gradually diminished. At rest, after exercise, ICA flow decreased further to a level of 8% below control flow within 5 minutes. PaCO2 increased significantly in average 1.6 mmHg during exercise. Cardiac output increased highly significantly (85%) during exercise. The ICA flow changes obtained during exercise in the present study indicate the presence of a regulatory mechanism counteracting the increasing perfusion pressure, but it is unable to compensate the decreased perfusion pressure when the body position was altered from supine to sitting. The cerebral vascular bed in the present patient material seems to operate above and below the lower limit of its pressure range for an adequate autoregulation.

Studies on arterial flow patients - instantaneous velocity spectrums and their phasic changes - with directional ultrasonic Doppler technique

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Intracortical distribution of renal blood flow in hemorrhagic shock in dogs

The effect of acute hypotensive hemorrhage on the intracortical distribution of renal blood flow was studied in anesthetized mongrel dogs with radioactive microspheres. In the early stages of shock, when carotid artery manipulation was avoided, outer cortical blood flow fell drastically and juxtamedullary flow was relatively well preserved. Carotid artery cannulation caused a redistribution of blood flow within the kidney even before hemorrhage, presumably by stimulating the carotid sinus reflex. Subsequently, with hemorrhage there was a parallel reduction in outer cortical and juxtamedullary blood flow. 138 Xe washout curves agreed with the microsphere findings. It was concluded that when the carotid artery was not disturbed, juxtamedullary blood flow was selectively preserved in the early stages of acute hypotensive hemorrhage.

Analysis of left ventricular function by atrial pacing

With the technique of right atrial pacing, left ventricular function was assessed in 21 normal subjects and in 13 patients with elevated left ventricular filling pressures. Since cardiac output does not change significantly with atrial pacing, the stroke volume decreases as an inverse function of the pacing rate. Stroke volume can thus be varied over a wide range, and by simultaneous measurement of left ventricular end-diastolic pressure, pacing ventricular function curves can be obtained. The calculated average slope for the ventricular function curve relating stroke volume index to left ventricular end-diastolic pressure was steeper in the normal subjects than in the group with elevated left ventricular end-diastolic pressure, but considerable overlap occurred between the groups. However, in individual patients the pacing ventricular function curve appears useful in assessment of the effect of interventions that augment or depress ventricular performance.

Extension of small-strain theory to finite deformation of cylindrical vessels by internal over-pressure

Calculations of the pressure distention of closed cylindrical vessels using classical infinitesimal-strain theory predict that, for isotropic materials, the length remains fixed while the diameter increases linearly with pressure. These predictions can be verified experimentally only if the radial deformation is less than 2–3%. This paper develops formulae applicable to deformations up to approximately 10 times the above, based on a modification of infinitesimal theory. The results predict significant lengthening of isotropic vessels, and ballooning or ‘blow-out’ above a certain pressure. It is shown that the classical stresses contain a common hydrostatic component which must be subtracted before the stresses can be integrated across the wall thickness to yield wall tensions. When the hydrostatic component is taken into account, Laplace’s law is found to hold for thick-walled vessels as well as for thin-walled vessels.