TY - JOUR
T1 - Sildenafil inhibits phosphodiesterase type 5 in human clitoral corpus cavernosum smooth muscle
AU - Park, Kwangsung
AU - Moreland, Robert B.
AU - Goldstein, Irwin
AU - Atala, Anthony
AU - Traish, Abdulmaged
PY - 1998/8/28
Y1 - 1998/8/28
N2 - Phosphodiesterases play an important physiological role by regulating the intracellular levels of cyclic nucleotides. In this study, we investigated the kinetic parameters of inhibition of phosphodiesterase (PDE) type 5 (EC 3.1.4.35, 3@?,5@?-cyclic GMP phosphodiesterase) by a novel, high-affinity, selective PDE type 5 inhibitor, sildenafil, in intact cells and in soluble extracts of human clitoral corpus cavernosum smooth muscle cells. Sildenafil inhibited cGMP hydrolysis in the crude extract (K(i) = 7.2 ± 2.7) and in partially purified preparations (K(i) = 9 nM) in a competitive manner, as determined by Dixon plots. Sildenafil was a more effective PDE type 5 inhibitor than zaprinast (K(i) = 400.0 ± 76.4 nM, crude extracts; 250 nM, partially purified). Stimulation of intracellular cGMP synthesis by the nitric oxide donor sodium nitroprusside resulted in a 3.3- and 2.9-fold increase in cGMP concentration in the presence of sildenafil or zaprinast, respectively, compared to sodium nitroprusside treatment alone in intact cells at physiological temperatures. These observations suggest that human clitoral corpus cavernosum smooth muscle tone may be regulated by the synthesis and release of nitric oxide and that this pathway is dependent on PDE type 5 activity.
AB - Phosphodiesterases play an important physiological role by regulating the intracellular levels of cyclic nucleotides. In this study, we investigated the kinetic parameters of inhibition of phosphodiesterase (PDE) type 5 (EC 3.1.4.35, 3@?,5@?-cyclic GMP phosphodiesterase) by a novel, high-affinity, selective PDE type 5 inhibitor, sildenafil, in intact cells and in soluble extracts of human clitoral corpus cavernosum smooth muscle cells. Sildenafil inhibited cGMP hydrolysis in the crude extract (K(i) = 7.2 ± 2.7) and in partially purified preparations (K(i) = 9 nM) in a competitive manner, as determined by Dixon plots. Sildenafil was a more effective PDE type 5 inhibitor than zaprinast (K(i) = 400.0 ± 76.4 nM, crude extracts; 250 nM, partially purified). Stimulation of intracellular cGMP synthesis by the nitric oxide donor sodium nitroprusside resulted in a 3.3- and 2.9-fold increase in cGMP concentration in the presence of sildenafil or zaprinast, respectively, compared to sodium nitroprusside treatment alone in intact cells at physiological temperatures. These observations suggest that human clitoral corpus cavernosum smooth muscle tone may be regulated by the synthesis and release of nitric oxide and that this pathway is dependent on PDE type 5 activity.
KW - cGMP
KW - Clitoral corpus cavernosum smooth muscle cells
KW - Female sexual dysfunction
KW - Phosphodiesterase type 5
KW - Sildenafil (Viagra)
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U2 - 10.1006/bbrc.1998.9206
DO - 10.1006/bbrc.1998.9206
M3 - Article
C2 - 9731184
AN - SCOPUS:0032575623
VL - 249
SP - 612
EP - 617
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
SN - 0006-291X
IS - 3
ER -