If a pharmaceutical company develops a drug selectively inhibiting phosphodiesterase type 6 (PDE6) in retinal photoreceptor cells, which consequence follows for a patient taking this drug?

💡 Explanation

PDE6 hydrolyzes cGMP, which is crucial for closing cation channels in photoreceptors; cones require rapid phototransduction. Inhibiting PDE6 elevates cGMP, desensitizing cones, because continuous depolarization overwhelms the cell's dynamic range; therefore, the result is impaired phototransduction in cone cells rather than enhanced rod function or improved adaptation.

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