We studied histamine metabolism, i.e., histldine decarboxylase (HD)-mediated synthesis and hlstamlnase-mediated catabollsm, in relation to intracellular histamine content in both aortic endothelial and subjacent smooth muscle cells of control and diabetic rats. Diabetes was Induced by a single jugular vein Injection of streptozotocln (55 mg/kg in acidified saline, pH 4.5), and animals were held for either 2 or 4 weeks following overt manifestation of diabetes. An additional 4-week diabetic group received Insulin (lletln NPH, 10 U per 24 hour) during the last week. With respect to control values, the histamine content of aortic endothelial cells increased 138%, HD activity Increased 250%, and histaminase activity decreased 50% over the 4-week period. In subjacent smooth muscle cells, the histamine content Increased In excess of 150%, HD activity Increased more than 300%, and histaminase activity decreased in excess of 30%. Insulin treatment for the last week resulted In complete reversal of all these changes. These results support the concept that a large vessel response similar to the microclrculatory prolonged phase of inflammation occurs In experimental diabetes, a change similar to that occurring in experimental atherosclerosis. They also Indicate that both synthetic and catabollc changes occur In histamine metabolism under these conditions, changes that alter arterlai wall histamine pools, and suggest that Insulin administration under conditions of experlmentai diabetes may modulate aortic histamine metabolism and the resultant Intraaortlc histamine pools.
Arteriosclerosis – Wolters Kluwer Health
Published: Mar 1, 1982