1, 25-Dihydroxyvitamin D Production Stimulated by Dibutyryl 3', 5'-Cyclic AMP in Normal Subjects and a Patient with Pseudohypoparathyroidism

UNAKAMI, H., FURUKAWA, Y., SOHN, H.E., YUMITA, S., MIURA, R., SASAKI, A., KOKUBUN, M., MIURA, Y., YOSHINAGA, K. and NAKANOME, C. 1, 25-Dihydroxyvitamin D Production Stimulated by Dibutyryl 3', 5'-Cyclic AMP in Normal Subjects and a Patient with Pseudohypoparathyroidism. Tohoku J. exp. Med., 1982, 138 (4), 411-418-Dibutyryl 3', 5'-cyclic AMP (DBcAMP) was infused in 4 normal subjects and a patient with pseudohypoparathyroidism (PHP) to study its effect on the production of 1, 25-dihydroxyvitamin D [1, 25(OH)2D]. In normal subjects, 2.5mg/kg of DBcAMP increased plasma 1, 25(OH)2D. reaching the peak at 6hr after infusion, while, 6.0mg/kg of DBcAMP delayed the peak to 12hr. The maximal increment of plasma 1, 25(OH)2D was 19.7±2.8pg/ml (mean±S.D.) in normals with 6.0mg/kg of DBcAMP and 12.2±1.0pg/ml (mean±S.D.) with 2.5 mg/kg, respectively. There was a significant difference between the doses (p<0.01). Plasma 24, 25-dihydroxyvitamin D [24, 25(OH)2D] showed no significant change after DBcAMP infusion in normal subjects. In a patients with PHP, however, 2.5mg/kg of DBcAMP markedly increased plasma 1, 25(OH)2D to reach the peak (48.9pg/ml) at 14hr and plasma 24, 25(OH)2D was decreased reciprocally. After DBcAMP infusion, depression of serum P, slight decrease in %TRP and the elevation of IRI were proved in normal subjects, while in a patient with PHP, there was a marked depression of %TRP. It is suggsted that the increments of plasma 1, 25(OH)2D by infusion of DBcAMP is dose-dependent in normal subjects, and that the 1, 25(OH)2D productivity by DBcAMP may be accelerated in a patient with PHP.