Degradation
Numerous cyclic nucleotide phosphodiesterases (PDE) can degrade cGMP by hydrolyzing cGMP into 5'-GMP. PDE 5, -6 and -9 are cGMP-specific while PDE1, -2, -3, -10 and -11 can hydrolyse both cAMP and cGMP.
Phosphodiesterase inhibitors prevent the degradation of cGMP, thereby enhancing and/or prolonging its effects. For example, Sildenafil (Viagra) and similar drugs enhance the vasodilatory effects of cGMP within the corpus cavernosum by inhibiting PDE 5 (or PDE V). This is used as a treatment for erectile dysfunction. However, the drug can inhibit PDE6 in retina (albeit with less affinity than PDE5). This has been shown to result in loss of visual sensitivity but is unlikely to impair common visual tasks, except under conditions of reduced visibility when objects are already near visual threshold. This effect is largely avoided by other PDE5 inhibitors, such as tadalafil.
Read more about this topic: Cyclic Guanosine Monophosphate
Famous quotes containing the word degradation:
“We found nothing grand in the history of the Jews nor in the morals inculcated in the Pentateuch.... I know of no other books that so fully teach the subjection and degradation of woman.”
—Elizabeth Cady Stanton (1815–1902)
“It was the most ungrateful and unjust act ever perpetrated by a republic upon a class of citizens who had worked and sacrificed and suffered as did the women of this nation in the struggle of the Civil War only to be rewarded at its close by such unspeakable degradation as to be reduced to the plane of subjects to enfranchised slaves.”
—Anna Howard Shaw (1847–1919)
“Why, since man and woman were created for each other, had He made their desires so dissimilar? Why should one class of women be able to dwell in luxurious seclusion from the trials of life, while another class performed their loathsome tasks? Surely His wisdom had not decreed that one set of women should live in degradation and in the end should perish that others might live in security, preserve their frappeed chastity, and in the end be saved.”
—Madeleine [Blair], U.S. prostitute and “madam.” Madeleine, ch. 10 (1919)