What is the physiological impact of phosphodiesterase inhibitors on cyclic GMP levels?

Phosphodiesterase inhibitors increase cyclic GMP levels, leading to enhanced smooth muscle relaxation.

Phosphodiesterase inhibitors increase cyclic AMP levels, leading to enhanced smooth muscle contraction.

Phosphodiesterase inhibitors decrease cyclic GMP levels, leading to reduced smooth muscle relaxation.

Phosphodiesterase inhibitors decrease cyclic AMP levels, leading to reduced smooth muscle contraction.