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, 2.5 mg/kg of DBcAMP increased plasma 1,25(OH)2D, reaching the peak at 6 hr after infusion, while, 6.0 mg/kg of DBcAMP delayed the peak to 12 hr. The maximal increment of plasma 1,25(OH)2D was 19.7+2.8 pg/ml (mean+s.D.) in normals with 6.0 mg/kg of DBcAMP and 12.2+1.0 pg/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, 2.5 mg/kg of DBcAMP markedly increased plasma 1,25(OH)2D to reach the peak (48.9 pg/ml) at 14 hr 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. dibutyryl 3',5'-cyclic AMP (DBcAMP); 1,25dihydroxyvitamin D [1,25(OH)2D]; 24,25-dihydroxyvitamin D [24,25(OH)2D]; pseudohypoparathyroidism (PHP)