Effect of type-selective inhibitors on cyclic nucleotide phosphodiesterase activity and insulin secretion in the clonal insulin secreting cell line BRIN-BD11.
1. The cyclic nucleotide phosphodiesterases (PDEs) present in an insulin secreting cell line, BRIN - BD11, were characterized using calcium/calmodulin, IGF-1, isoenzyme-selective PDE inhibitors and RT - PCR. 2. Calmodulin activated cyclic AMP or cyclic GMP PDE activity in pellet and was 3 fold (P=0.002) more potent in activating cyclic nucleotide hydrolysis in pellet compared with supernatant fractions. 3. The PDE1/PDE5 inhibitor zaprinast inhibited both cyclic AMP and cyclic GMP PDE activity in both pellet and supernatant fractions of cell homogenates by a maximum of around 25% (IC(50) 1 - 5 microM), while rolipram (PDE4 selective) inhibited only cyclic AMP hydrolysis. 4. The PDE3-selective inhibitors Org 9935 (0.02 - 10 microM) and siguazodan (0.1 - 10 microM) inhibited cyclic AMP PDE activity in the pellet but not the supernatant fractions of cell homogenates, with a maximum inhibition of about 30%. IGF-1 (2 - 7.5 ng ml(-1)) potently augmented this PDE activity. 5. RT - PCR using specific primers for PDE3B, but not for PDE3A, amplified, from BRIN - BD11 cell total RNA, a 351 base pair product that was >97% homologous with rat adipose tissue PDE3B. 6. IBMX, Org 9935, siguazodan and rolipram (1 - 50 microM), but not zaprinast, each augmented glucose-induced insulin secretion in the presence of 16.7 mM but not 1 mM glucose. 7. These findings, in a clonal insulin secreting cell line, are consistent with an important role for PDE3B in regulating the pool of cyclic AMP relevant to the modulation of glucose-induced insulin secretion.
Ahmad
M
M
Department of Physiology and Pharmacology, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, Taylor Street, Glasgow,UK. Coleraine, Northern Ireland, BT52 1SA.
Abdel-Wahab
Y H
YH
Tate
R
R
Flatt
P R
PR
Pyne
N J
NJ
Furman
B L
BL
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000494:pharmacology; D002999:Clone Cells; D000242:Cyclic AMP / Q000494:pharmacology; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1; D005947:Glucose / Q000494:pharmacology; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D008969:Molecular Sequence Data; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D011688:Purinones / Q000494:pharmacology; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction
D002147:Calmodulin; D007328:Insulin; D010726:Phosphodiesterase Inhibitors; D011688:Purinones; D007334:Insulin-Like Growth Factor I; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054677:Cyclic Nucleotide Phosphodiesterases, Type 1; C011145:zaprinast; D005947:Glucose; D002118:Calcium; D015056:1-Methyl-3-isobutylxanthine