TY - JOUR T1 - STUDIES ON THE RESPONSE OF THE ISOLATED INTESTINE TO ERGOTAMINE WITH SPECIAL REFERENCE TO THE INFLUENCE OF IONS JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 315 LP - 337 VL - 45 IS - 3 AU - WILLIAM SALANT AU - WILLIAM M. PARKINS Y1 - 1932/07/01 UR - http://jpet.aspetjournals.org/content/45/3/315.abstract N2 - 1. Strong concentrations of ergotamine (1:50,000 to 1:33,000) in Locke solution containing about 25 to 30 per cent defibrinated blood causes no effect or slight depression. Concentration of 1:200,000 or even 1:100,000 ergotamine in Locke-blood solutions sometimes produced stimulation. The results were the same with blood from untreated cats and from those that had received ergotamine previously. 2. Weak solutions of ergotamine (1:1,000,000 to 1:500,000) in normal Locke produced stimulation but more frequently depression in the cat intestine, stimulation or no effect in the rabbit and no action in the rat intestine. 3. Medium and stronger concentrations of ergotamine (1:100,000 to 1:50,000) in normal Locke usually depressed considerably motor activity in the cat intestine, less in the rabbit intestine but depression was generally intense in the rat intestine. The lower portion of the intestine was more sensitive than the upper, to ergotamine. 4. The difference of the isolated intestine and of the intestine in situ to ergotamine may be due the action of the blood in decreasing the depression by ergotamine or to increased sensitiveness of the parasympathetic or both. Depression by larger doses of ergotamine is probably due to the same mechanism in the isolated intestine and in the intestine in situ. 5. By lowering the pH to about 6.7 to 6.4 the depression by ergotamine was increased in the intestine of cats and of the rabbits in which the contractions also became irregular. But ergotamine was less depressant or stimulated the rat intestine when the pH was decreased to about 6.5. 6. Excess calcium may decrease or prevent the depression by ergotamine in the intestine of the cat, rabbit and rat. The effect of increased calcium on ergotamine was in some cases the same as that of normal amounts. The effect of calcium was greater when the pH of the solution was low (pH 6.5), stimulation by medium and larger amounts of ergotamine being occasionally produced. Stimulation by ergotainine also occurred when Ca was increased three times or more of the normal amount when pH was 7.5. Deficient calcium increased the depression produced by ergotamine in cats and rabbits. 7. Excess potassium, provided the concentration was doubled or trebled increased the depression of the intestine by ergotamine in all animals. Ergotamine in K-free Locke was only slightly depressant in the rat intestine. 8. The response of the intestine to ions alone was as follows: a. A decrease of the pH from 7.8 to about 7.2 or a little below was usually without effect or was followed by slight depression of intestinal motility in the intestines of the cat and rabbit. Decrease from about 7.7 or 7.5 to 6.5 caused depression. Decrease of pH to 6.5 was also followed by depression of the rat intestine, but on the whole the response was irregular in these animals. b. Calcium when increased 50 to 100 per cent of the content of normal Locke provoked moderate stimulation of the cat intestine, depression or no effect in the rabbit intestine, and intense stimulation of the rat intestine even by small as well as large amounts. Powerful stimulation was also observed in the cat intestine when calcium in any amount was added to solutions containing little or no calcium. c. Increased potassium caused intense stimulation or occasionally moderate depression in the intestine of the cat. Stimulation followed by depression and usually irregularity of action in the intestine of the rabbit when potassium was increased 100 to 200 per cent. Potassium up to 50 mgm. (KCl) per 100 cc. added to K-free solution caused inhibition in rats. The same amounts of 10 to 20 mgm. or more added to solutions containing 0.020 per cent or more KC1 produced marked stimulation. ER -