| Research Abstract |
To evaluate the mode of neural and humoral control on venous smooth muscles, we have undertaken to study regional differences in the density of aminergic nerve fibers of the rabbit, canine, and monkey venous walls by glyoxylic acid-histochemical techniques, and in the potency in vasoconstrictive and vasodilative responses of isolated canine and monkey smooth muscles. The experimental results are summarized as follows: (1) The aminergic nerve fibers innervate most densely in the portal vein, inferior caval vein, renal vein, and common iliac vein. (2) The nerve fibers present sparsely in the venous walls of femoral vein and lateral saphenous vein at the intramuscular portion. (3) The heterogeneity in the aminergic innervation was observed in the monkey, canine, and rabbit venous system, but the density of aminergic nerve fibers was highest in the monkey veins and lowest in the rabbit. (4) There were marked heterogeneity in pharmacological responses to vasoconstrictive and vasodilative agents in isolated monkey and canine veins. (5) Thus, from the pharmacological points of view, the responsiveness of venous smooth muscle was divided as following three groups: (1) abdominal caval vein, iliac veins, renal vein, and portal vein; (2) thoracic caval vein, extremity veins, and cervical veins; (3) axillar vein and subclavian vein. (6) In monkey venous system, the third group was not distinguished, therefore the third grouped veins may be a characteristic feature of the pharmacological responses of venous smooth muscles in animal with four extremities, comparing with monkey and human being.
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