Nathanson J A
Invest Ophthalmol Vis Sci. 1987 Aug;28(8):1357-64.
Atriopeptins are a recently-discovered group of polypeptides secreted from cardiac myocytes in response to fluid overload. The present studies demonstrate that atriopeptin receptors, coupled to the activation of guanylate cyclase, are present in rabbit ciliary process. Rat atrial natriuretic peptide 1-28 (rANP) activated ciliary process guanylate cyclase activity with a Vmax of from 24-337% and with a Ka of from 0.4-4 nM, similar to that for atriopeptin receptors present in rabbit kidney. Activation was greater for the intact peptide than for rANP fragments 1-11 or 13-28, and stimulated activity was greater in isolated ciliary processes than in ciliary muscle or iris. Intravitreal injection of the complete peptide into living rabbits caused a marked decrease in IOP in the ipsilateral eye which persisted for more than 48 hr and occurred without evidence of an inflammatory response. There was a smaller decrease in IOP in the contralateral eye. Following intravitreal injection of rANP 1-28, atriopeptin levels in aqueous humor remained elevated for at least 44 hr. Injection of the biochemically less active rANP fragments 1-11 and 13-28 caused no decrease in IOP. These physiological data, together with the biochemical identification of atriopeptin receptors and second messenger systems in the ciliary process, suggest that certain tissues of the anterior segment may be atriopeptin end-organs and that agents acting at atriopeptin receptors may be able to regulate IOP.
心房肽是最近发现的一类由心肌细胞分泌以应对液体过载的多肽。目前的研究表明，与鸟苷酸环化酶激活偶联的心房肽受体存在于兔睫状体中。大鼠心房利钠肽1 - 28（rANP）激活睫状体鸟苷酸环化酶活性，其最大反应速度（Vmax）为24% - 337%，解离常数（Ka）为0.4 - 4 nM，类似于兔肾中存在的心房肽受体。完整肽的激活作用大于rANP片段1 - 11或13 - 28，并且在分离的睫状体中刺激活性大于睫状肌或虹膜。向活兔玻璃体内注射完整肽导致同侧眼眼压显著降低，这种降低持续超过48小时，且无炎症反应迹象。对侧眼眼压降低幅度较小。玻璃体内注射rANP 1 - 28后，房水中心房肽水平至少44小时保持升高。注射生化活性较低的rANP片段1 - 11和13 - 28未引起眼压降低。这些生理学数据，连同睫状体中心房肽受体和第二信使系统的生化鉴定，表明眼前段的某些组织可能是心房肽终末器官，并且作用于心房肽受体的药物可能能够调节眼压。
