Abstract
1. Alpha-lobelin is one of four alkaloids of Lobelia-inflata which have been isolated and whose chemical composition seems well established.
2. The work here reported deals with the action of intravenous injections of alpha-lobelin in the dog, cat, monkey, rabbit and man, in conditions of depression due to amytal, morphine, veronal, ether, carbon monoxide (illuminating gas), carbon dioxide and increased intracranial pressure.
3. The action of alpha-lobelin on the respiration and on arterial pressure as reported by previous investigators is in the main confirmed.
4. The respiration can be markedly, even tremendously, increased in the intact animal or in man, in light and in moderate anesthesia. Marked individual differences in the degree of response are seen. The respiratory effects are of brief duration.
5. Arterial pressure can also be raised in a striking manner and maintained at a level above the original one for as long as six minutes or more in animals depressed to certain degrees.
6. In deeply depressed animals, arterial pressure can be lowered by doses of alpha-lobelin which in lesser degrees of depression stimulate respiration and raise the pressure. In these animals the respiratory stimulation is likely to be slight or to fail altogether.
7. The extent and duration of the pressure fall vary with the size of the dose of lobelin and depth of anesthesia. A fall of pressure that is fatal can easily be obtained.
8. The reactions responsible for this effect are discussed and the danger of intravenous injections of alpha-lobelin is emphasized.
9. There is a striking similarity between the action of alpha-lobelin and adrenine as regards (a) the respiration, (b) the blood pressure effects of the two substances, and (c) their hyperglucemic effects, which have not been hitherto described in relation to lobelin. The relation of these various actions of adrenine and lobein are discussed.
10. The side actions and toxicity of alpha-lobelin are briefly considered.
Footnotes
- Received July 18, 1927.
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