Percy Lindgren

Activation of Sympathetic Vasodilator and Vasoconstrictor Neurons by Electric Stimulation in the Medulla of the Dog and Cat

Electric stimulation in the ventrolateral area of the medulla elicited vasodilation in skeletal muscles, and vasoconstriction in the skin and intestines. The vasodilation was accredited to activity in the cholinergic sympathetic vasodilator outflow previously shown to originate in the motor cortex of the dog. The possible functional significance of the vasodilator fibers in regulating muscle blood flow during exercise is discussed.

Vascular reaction to water-soluble contrast media. Significance of concentration and totral amount of iodine.

The modern contrast media used for angiographic investigations must have a certain iodine content in order to produce the roentgenographic density necessary for good demonstration of the vessels. This goal, good contrast filling, may be accomplished with concentrated solutions of substances having a high amount of iodine in the molecule. Modern water-soluble media for intraarterial and intravenous injections all hold three iodine substitutions in the molecule, placed in 2-, 4and 6-positions in a 6-carbon ring, the iodine constituting about 60 % of the molecular weight. From the pharmacologic point of view, the concentration of a contrast medium solution, and hence e. g. the osmolarity, has always been considered a logical classification basis. Since certain side effects may be due to the high concentration of the contrast medium, the solutions should be kept reasonably dilute. This is however to a great extent prevented by the roentgenologic need to keep a high iodine content per volume for obtaining as good a contrast as possible.

Circulatory effects of iothalamate compounds (Conray) and contrast media of the benzoic acid type.

It is obvious that circulatory side effects may occur in connection with roentgen examinations involving parenterally administered contrast media. These may be due for example to changes in the elements formed in the blood (erythrocyte aggregation), to an influence on cardiac function, a direct action on the blood vessels, or an effect on the autonomic centers of the nervous system. These factors have for a number of years been investigated experimentally by the present authors (LINDGREN & TORNELL 1958, KAGSTROM, LINDGREN & TORNELL 1958, 1960, LINDGREN & SALTZMAN 1962, TORNELL 1963, LINDGREN, LOFSTROM & SALTZMAN 1964). One of the most consistent observations was the great difference in circulatory reactions between acetrizoate and diatrizoate preparations, the latter being much less pharmacologically active than the former, in spite of the fact that both are tri-iodo-benzoic acid derivatives. This difference has also been reported by numerous other investigators, and a surprisingly good correlation

Localization and Function of the Medullary Vasomotor Center in Infracollicularly Decerebrated Cats

The medullary vasomotor centers were studied in three cats, decerebrated below the mesencephalon four to nine days before the acute experiment. Exploration of the dorsal regions of the medulla oblongata revealed that the vasomotor active regions had about the same extension as in intact animals. Medullary pressor and depressor reflexes, elicited by electrical stimulation of a peripheral nerve and a sinus nerve, were also of a normal type in the decerebrated cats. The results indicate that the medullary vasomotor center constitutes a region of nuclear character with cell bodies and synapses functioning as a tonic and reflex center. In this respect, it seems to function normally even after the degeneration of vasomotor pathways from higher centers.