Voltage-clamp measurements on single split lamellae of posterior gills of the shore crabCarcinus maenas
✍ Scribed by H. Onken; D. Siebers
- Publisher
- Springer-Verlag
- Year
- 1992
- Tongue
- English
- Weight
- 606 KB
- Volume
- 114
- Category
- Article
- ISSN
- 0025-3162
No coin nor oath required. For personal study only.
✦ Synopsis
Single split lamella preparations of posterior gills of low-salt adapted shore crabs Carcinus maenas (collected from the Kiel Bay, Baltic Sea in 1991) were mounted in a micro Ussing-chamber. With NaC1 salines on both sides we found an outside positive potential difference (PD) of 6.6 _+ 1.3 mV, a short-circuit current (Iso) of -240 _+ 65 ~Acm -z and a resistance (R,) of 25 _+ 3 ~cm 2 (n = 8). Substitution of C1-(gluconate) on both sides of the preparation resulted in a decrease of Iso by more than 90 % at constant R,. Is~ disappeared and R, increased after substitution of Na + (choline). When ouabain (2 mmol 1-1) was applied to the internal NaCl-saline, Isc decreased and R, remained unchanged. Internal addition of 0.1 mmol 1-1 acetazolamide left Isc and R, unaffected. Application of amiloride to the external NaC1 saline resulted in an increase of both inward negative Isc and Rt. The dose dependence of the diuretic showed a maximal effect between 50 and 200 gmol 1-1 with a halfmaximal blocker concentration (KAMI) of ca. 10 gmol 1-1. The results show that the split lamella preparation of posterior gills of C. maenas is a low resistance epithelium which is able to effect a massive, electrogenic and coupled absorption of Na + and C1-.