Amiloride-sensitive sodium absorption is different in vertebrates and invertebrates

• DOI: 10.1152/ajpregu.00549.2006
• Publication Date: 2007-03-02T04:13:51Z
• Authors: Katja Sobczak; Anne Willing; Kristina Kusche; Nadine Bangel; Wolf-Michael Weber
• Keywords: Epithelial sodium channel; Amiloride; Hirudo medicinalis; Annelid; Integument; Eledoisin

Amiloride-sensitive Na + absorption is a well-described feature of numerous transporting epithelia in vertebrates. Yet, very little known about this important physiological process regarding invertebrates. In the present paper, we compare vertebrate mediated by amiloride-sensitive epithelial channel (ENaC) and its invertebrate counterpart. We used dorsal skin annelid Hirudo medicinalis as model for epithelia. applying electrophysiological, molecular, biochemical techniques found striking functional structural differences between absorption. Using modified Ussing chambers, analyzed influence different blockers effectors ENaC on leech demonstrate that serine protease trypsin had no effect transport across integument, while it strongly activates ENaC. While protons, divalent cations Ni 2+ Zn stimulate ENaC, currents integument were substantially reduced. For molecular studies, constructed cDNA library screened with specific antibodies. performed PCR approaches using vast number degenerated primers to identify ENaC-like structures. both strategies did not reveal any sequence integument. From these data conclude an but still unknown member ENaC/DEG family termed lENaTP (leech protein).