Question

In the presence of adrenaline, would glycogen levels in muscle cells that lack the cAMP phosphodiesterase be higher or lower than in normal cells treated with adrenaline?

1) higher
2) lower

Answer 1

Glycogen levels in muscle cells that lack the cAMP phosphodiesterase would be higher than in normal cells treated with adrenaline.Option 1 is the correct answer.

Step-by-step explanation:

In the presence of adrenaline, glycogen levels in muscle cells that lack the cAMP phosphodiesterase would be higher than in normal cells treated with adrenaline.

Adrenaline activates β-adrenergic receptors, leading to an increase in cyclic AMP (cAMP) inside the cell. This cAMP activates protein kinase A (PKA), which phosphorylates two enzymes. The first enzyme, glycogen phosphorylase, promotes glycogen degradation, leading to the production of glucose from glycogen. The second enzyme, glycogen synthase, is inhibited, preventing the formation of glycogen from glucose.

Therefore, in the absence of cAMP phosphodiesterase, which degrades cAMP, the levels of cAMP would be higher, resulting in increased activation of PKA and further glycogen degradation. This would lead to higher glycogen levels compared to normal cells treated with adrenaline.

In the absence of cAMP phosphodiesterase, which degrades cAMP, adrenaline-induced activation of β-adrenergic receptors elevates intracellular cAMP levels. Heightened cAMP activates protein kinase A (PKA), intensifying glycogen phosphorylase activity, promoting glycogen breakdown, and inhibiting glycogen synthase. Consequently, muscle cells lacking cAMP phosphodiesterase exhibit increased PKA activation, leading to enhanced glycogen degradation, resulting in higher glycogen levels compared to normal cells treated with adrenaline.