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Biomedical subjects

J Gero

Publications and source records attributed to J Gero.

32 records · Page 2Linked to original sources
PubMed1975

Diffusion through the vessel wall of transmitter released by sympathetic stimulation. A fluorescence and Autoradiography study.

The disposition of sympathetic transmitter within the wall of rat femoral and rabbit saphenous arteries has been studied during sympathetic stimulation. Using a histochemical fluorescence technique, sharply delineated bead-like fluorescent spots representing sympathetic nerve terminals were found at the adventitio-medial junction. In specimens excised during sympathetic nerve stimulation, the entire media was veiled by fluorescent material representing noradrenaline which had diffused into that layer after release. The localization of the nerve terminals in controls as well as diffusion of transmitter during stimulation in the rat femoral artery was corroborated by autoradiography of tritiated noradrenaline.

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PubMed1975

The ability of collecting veins to sustain sympathetic constriction.

The collecting femoral vein is capable of sustaining contraction even for 15 minutes provided sympathetic stimulation frequency is low or moderate. At a frequency of 15 Hz, however, the collecting vein gradually relaxes after having reached a maximum contraction in spite of continuing stimulation. The ability of the relaxing venous smooth muscle to develop further contraction to exogenous noradrenaline has been proved. It seems probable that the relaxation is due to the decline in the amount of transmitter released from nerve terminals as a result of prolonged high rate stimulation.

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PubMedDate not supplied

Geometry of the conduit coronary artery in diastole is determined by the volume of the left and right ventricles.

In the canine heart placed in a bath the ramus interventricularis anterior (RIA) was perfused under constant pressure. Segment length and diameter of RIA were monitored by ultrasound technique, coronary pressure by electromanometer. Increasing the volume of the left ventricle by up to 150% of the physiological value increased the segment length by 3.73-12.72% and decreased the diameter by 3.14-9.37%. Similar increments of right ventricular volume increased coronary segment length by 4.38-13.02% and decreased diameter by 2.85-16.45%. In concert with the dynamics of heart deformation segment length and diameter changes were larger in the proximal (close to the basis of the heart) than in the distal part of the artery (close to the apex). Implications of this phenomenon in physiological and/or pathophysiological regulation processes are presented. The results have a methodological implication for in situ studies of coronary smooth muscle activity. When the diameter of the coronary artery is taken as an indicator of smooth muscle activity the ventricular volumes should be kept constant.

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