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Biomedical subjects

T Togawa

Publications and source records attributed to T Togawa.

At least 163 records · Page 9Linked to original sources
PubMed1980

Adaptive regulation of wall shear stress to flow change in the canine carotid artery.

To study the adaptive response of the vascular wall to blood flow changes, an arteriovenous shunt was constructed between the common carotid artery and the external jugular vein in 12 dogs. Six to eight months postoperatively, the arterial internal radius (r) was determined by angiography and/or the use of pressure-volume relationship. The results showed that r increased with increased flow load (f) and vice versa. Wall shear rate (gamma) was calculated from gamma = 4f/(tau r3), assuming laminar flow. The value of gamma, initially proportional to f, had recovered almost to the control level (within 15%) due to the vessel dilatation or atrophy during the chronic experiment, when f was less than 4 times the control. Transendothelial protein permeability, evaluated at the T-1824-stained surface by a reflectometric method, also showed a close correlation with wall shear (r = 0.934). A local autoregulatory mechanism of wall shear stress involving protein turnover in the vascular wall is suggested.

Adaptation, Physiological↗
PubMed1979

Indirect measurement of instantaneous arterial blood pressure in the rat.

We devised a hydraulic servo-control system for indirect blood pressure measurement in the rat's tail, by which beat-to-beat systolic and diastolic blood pressure can be obtained. In this method the principle of "unloading vascular wall" proposed by Shirer (1962) is employed. The proposed system is composed of a transmittance photoelectric plethysmograph with an occluding cuff, a small diaphragm actuator for compressing and decompressing the segment by the hydraulic pressure, and an electromagnetic shaker driven by a volume servo circuit in accordance with the signal from the photoelectric plethysmograph. The plethysmographic signal is clamped at a proper value corresponding to the unload vascular volume by the instantaneous hydraulic servo control. The cuff pressure thus automatically controlled follows the intra-arterial pressure in the tail segment. The accuracy of this method was evaluated in comparison with direct measurement of blood pressure recorded simultaneously from 16 unanesthetized spontaneously hypertensive and normotensive rats. Close agreement between the simultaneous data from these two methods were observed.

Animals↗