"Basal" AC activity

28 March 2001

Md. Shahidul Islam

In the cells that I commonly work with, i.e. pancreatic beta cells or tumor cell lines derived from them, it has been reported many times that if you just add some PDE inhibitors to a cell suspension, cAMP level increases. This may mean that there is some basal activity of AC in these cells, even in the apparent absence of ligand binding.

However the meaning of "basal" is ambiguous here. This may mean that low level of unidentified ligands secreted from the same cells (autocrine) or neighbouring cells (paracrine) cells are active on the receptors linked to AC. This low level of receptor activation does not increase cAMP a lot but is visible once PDE is inhibited. The situation in the cell is complex in this way.

What happens in the test tube can be speculated. It is possible that there are some endogenous forskolin-like molecules and these may maintain some basal activity of the enzyme.