Klotho gene product may have a role to regulate VEGF and p21 and tightly linked to the endothelial function to release NO

通过体内诱变，建立了一种新的小鼠衰老模型(KL/KL小鼠)。我们研究了该菌株的内皮功能。取6~9周龄野生型(+/+)、杂合子(+/KL)和纯合子(KL/KL)小鼠胸主动脉环标本。与+/+小鼠相比，KL/+小鼠的主动脉对去甲肾上腺素的收缩反应增强，对乙酰胆碱和卵磷脂超氧化物歧化酶(SOD)的血管扩张反应减弱。对硝普钠的反应不变。N^G-硝基-L-精氨酸甲酯对去甲肾上腺素的收缩作用在+/+小鼠中比在KL/+小鼠中更明显。LNAME可消除KL/+小鼠对乙酰胆碱和卵磷脂的血管扩张反应。与+/+小鼠相比，KL/+小鼠的NO代谢产物(NO_2^-和NO_3^-)和尿中cGMP显著减少。而尿液中6-酮前列腺素F1α排泄量无明显变化。KL/+小鼠主动脉中NO合成酶和血管内皮生长因子(VEGF)的免疫染色较低，细胞周期依赖性激酶抑制因子p21的免疫染色较高。Klotho基因产物可能具有调节血管内皮生长因子和p21，保护内皮细胞免受细胞衰老的作用，并与内皮功能密切相关，从而释放NO。

A novel murine model of aging (kl/kl mice) was developed by in vivo mutagenesis. We investigated the endothelial function in this strain. Ring preparations of the thoracic aorta were obtained from wild-type (+/+), heterozygous (+/kl) and homozygous (kl/kl) mice for the transgene at age 6 to 9 weeks. The aorta of kl/+ mice showed an exaggerated contractile response to norepinephrine and attenuated vasodilator responses to acetylcholine and lecithinized superoxide dismutase (SOD) as compared with those of +/+ mice. The reseponse to sodium nitroprusside was unaltered. The contraction to norepinephrine was augmented by treatment with N^G-nitro-L-arginine methyl ester (LNAME) 10^<-5> M, more so in +/+ mice than in kl/+ mice. The treatment with LNAME abolished the vasodilator responses to both acetylcholine and lecithinized SOD.NO metabolites (NO_2^- and NO_3^-) and cyclic GMP in urine were significantly reduced in kl/+ mice compared with +/+ mice. However, urinary excretion of 6-keto prostaglandin F1α was unaltered. Immunostaining of NO synthase and vascular endothelial growth factor (VEGF) was low and immunostaining of cell cycle-dependent kinase inhibitor p21 was elevated in the aorta of kl/+ mice. No immunostaining of NO synthase was noted in the aorta of kl/kl mice.Klotho gene product may have a role to regulate VEGF and p21, protect endothelial cells from cellular senescence and tightly linked to the endothelial function to release NO.