Why is it important that muscle cells have low levels of glutamate dehydrogenase?

Glutamate dehydrogenase (GDH) is anenzyme which converts glutamate to $\alpha$-ketoglutarate in areversible manner. Incorporating ${\text{NH}}_4^{+}$allows$\alpha$-ketoglutarate to be converted back to glutamate.

Because the purine nucleotide cycleproduces fumarate,the citric acid cycle is aided in muscle cells by the purine nucleotide cycle. The citric acid cycle's intermediary is fumarate.

During in the conversion of AMP (adenosine monophosphate) to IMP, the purine nucleotide cycle creates ${\text{NH}}_4^{+}$. (Inosine monophosphate). Glutamate dehydrogenase with high activitycan generate glutamate from $\alpha$-ketoglutarate using ${\text{NH}}_4^{+}$. This reaction would hinder the energy generation mechanism because $\alpha$-ketoglutarate is a citric acid cycle intermediary.

Because glutamate dehydrogenase can utilise the ammonium ion produced by the purine nucleotide cycle to make glutamate from alha-ketoglutarate, muscle cells must contain low quantities of this enzyme.