Distribution of adenylyl cyclase and guanylyl cyclase in rat tissues

الملخص EN

The specific activities of adenylyl and guanylyl cyclases, the cAMP and cGMP phosphodiesterase of rat kidney, liver, heart and brain were examined.

Of all tissues, kidney has the highest adenylyl cyclase specific activities by mean (± SD) of (145 ± 14 pmol/min/mg protein) followed by that of heart (113 ± 21 pmol/min/mg protein), brain (101 ± 8 pmol/min/mg protein) and liver (92 ± 9 pmol/min/mg protein).

The specific activity of particulate guanylyl cyclase was the highest in liver (26 ± 1 nmol/min/mg protein), but the soluble form predominated in kidney (40 ± 2 nmol/min/mg protein).

In contrast to the other tissues examined, brain showed relatively high cAMP and cGMP phosphodiesterase activities.

The kinetic properties of the adenylyl cyclases and cAMP phosphodiesterases were also investigated.

The optimum pH for both types of activity was found to be at 7.4.

Subcellular fractionation of the kidney to locate adenylyl cyclase activity revealed that both the mitochondrial and the microsomal fractions had higher specific activities than that of the nuclear fraction.

Studies on the tissue distribution of cyclic nucleotide PDE activity as well as adenylyl and guanylyl cyclase showed that it is widely distributed in intra and extracellular and they have an important role in signal and nucleotide transdaction.