Studies on the properties of 3-N-[3-[3-(1-piperidinomethyl)phenoxy]-propyl]amino-4-amino-1,2, 5-thiadiazole-1-oxide (L-643,441) as an H2-receptor antagonist in isolated gastric glands.

The H2-receptor blocking properties of L-643,441 were compared with ranitidine in isolated rabbit gastric glands. [14C]Aminopyrine uptake was used as the indicator of gastric acid secretion. Unlike ranitidine, inhibition by L-643,441 was time-dependent, only partially reversible, and was not surmounted by increasing doses of histamine. These and other findings are similar to those found previously in guinea pig atria, providing further evidence that at the receptor level, the mechanism of action of L-643, 441 is different from standard H2-receptor antagonists such as ranitidine.