Abstract
1. The effect of large doses of histamine, acetylcholine, pilocarpine, and potassium chloride on the responsiveness of isolated guinea pig intestine was investigated.
2. Maximal contractions obtained in response to a large dose of histamine, acetylcholine, pilocarpine, barium chloride, and mecholyl were followed by temporary depression of the contractile responsiveness of the intestinal strip. On the other hand, a maximal contraction in response to large doses of potassium chloride did not result in a decreased contractility of the preparation.
3. A small increase in the K/Ca ratio of the perfusion fluid, such as obtained by doubling the potassium content of Tyrode solution, was sufficient to neutralize the effect of large doses of histamine, acetylcholine, pilocarpine, barium chloride, etc.
Footnotes
- Received May 8, 1946.