Nicotinamide Modulation of Rat Pancreatic Islet Cell Responsiveness In Vitro[*]

Abstract

The influence of nicotinamide (NA), a highly suitable precursor substrate for NAD synthesis in various tissues, on islet cell responsiveness was determined. After a 30 minute perifusion with this compound, nicotinamide, in a dose-dependent manner, potentiated glucose-induced insulin secretion. Maximal potentiation (approximately 250%) was observed at 20 mM NA and the threshold for potentiation was 3 mM. In the absence of glucose, NA did not affect basal secretion rates. Mannoheptulose blocked the primary stimulant action of glucose and the potentiating effects of NA. NA did not alter the rate of glucose usage by isolated islets. These results further underscore the possible importance of pyridine nucleotides in stimulated secretion.

Key words

Insulin-Release - Nicotinamide - Pyridine Nucleotides - Glucose Metabolism

1 Supported by USPHS Grant AM 10591, AM 17810, the Diabetes and Endocrinology Centers Grant AM 17901, and a grant from the American Diabetes Association. Dr. Zawalich is the recipient of Elliott P. Joslin Research and Development Award from the American Diabetes Association; Dr. Matschinsky is an Established Investigator of the American Diabetes Association.

1 All experiments reported in the paper were conducted at the Departments of Pediatrics and Pharmacology, Washington University School of Medicine, St. Louis, MO, 63110 (U.S.A.)

1 Supported by USPHS Grant AM 10591, AM 17810, the Diabetes and Endocrinology Centers Grant AM 17901, and a grant from the American Diabetes Association. Dr. Zawalich is the recipient of Elliott P. Joslin Research and Development Award from the American Diabetes Association; Dr. Matschinsky is an Established Investigator of the American Diabetes Association.

1 All experiments reported in the paper were conducted at the Departments of Pediatrics and Pharmacology, Washington University School of Medicine, St. Louis, MO, 63110 (U.S.A.)