American journal of physiology . ould be immediately mani-fest in the splanchnic area, the injection was made into theleft carotid artery close to the aorta. Injection of the adrenalin solution is followed immediatelyby a rise in blood pressure, the index to the sympathetic nervouscontrol of the blood vessels. The vasoconstriction in this caseis probably in the region of the coehaco-mesenteric arteries, but Vasomotor Phenomena in the Turtle 241 it is not possible to state definitely that all occurs in this regionbecause some of the extract may find its way past these arteriesand into the dorsa
American journal of physiology . ould be immediately mani-fest in the splanchnic area, the injection was made into theleft carotid artery close to the aorta. Injection of the adrenalin solution is followed immediatelyby a rise in blood pressure, the index to the sympathetic nervouscontrol of the blood vessels. The vasoconstriction in this caseis probably in the region of the coehaco-mesenteric arteries, but Vasomotor Phenomena in the Turtle 241 it is not possible to state definitely that all occurs in this regionbecause some of the extract may find its way past these arteriesand into the dorsal aorta, in which case it may then be distrib-uted to the kidneys, the genital organs and the posterior ex-tremities. In the tracing (Fig. i) it will be noted that the inter-val between the injection of the adrenahn (indicated by the breakupon the base Hne) and the beginning of the rise in blood pressureis actually about fifteen seconds. This short period favors theview that the vasoconstriction is in the region of the coeliaco-. FiGURE 1. The rise in the blood pressure following an injection of a 1:2000 solution ofadrenalin. Initial pressure 14 mm. Hg Maximum pressure 30 mm. Hg. Timeline in seconds. mesenteric arteries since the actual distance to this area issomewhat less than to the other possible organs. The bloodpressure after the rise may be more than double the original,and the phase of maximum pressure is always several minutesin duration. A complete return to the previous pressure re-quires from twenty to thirty minutes, indicating that the bloodvessels hold their tone for a considerable time under the influ-ence of a small amount of adrenalin. Two additional points are shown in the blood pressure trac-ings, namely, an augmentor effect upon the heart, and an inter-rupted heart rhythm. The former effect is so well known thatmere mention of it is sufficient; the latter phenomenon, how-ever, is not so well understood, but a discussion of it fallsproperly under a later div
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