INHIBITORY EFFECT OF DIBUTYRYL CYCLIC AMP ON THE RELEASE OF CALCIUM, INORGANIC PHOSPHATE AND LYSOSOMAL ENZYMES FROM CALVARIAL BONES CULTURED FOR 24 HOURS

Abstract

ABSTRACT The effect of N6,O2′-dibutyryl adenosine 3′,5′-cyclic-monophosphate (dbcAMP) on the mobilization of calcium (Ca2 +), inorganic phosphate (Pi) and lysosomal enzymes was studied in a bone culture system for 24 h using half calvaria from 6–7 day-old mice. DbcAMP inhibited spontaneous as well as parathyroid hormone-stimulated mineral mobilization. DbcAMP in a concentration of 5 × 10−4m also reduced the activities of β-glucuronidase, β-galactosidase and acid phosphatase found in the media while the activities of lactate dehydrogenase, aspartate aminotransferase and alanine aminotransferase were not affected. It is concluded that cAMP is not a stimulator but an inhibitor of bone resorption within the culture period studied (24 h) and that the cyclic nucleotide might interfere with release processes involved in bone resorption.