| Autor: |
Jensen, F. B., Brahm, J., Koldkjær, P., Wang, T., McKenzie, D. J., Taylor, E. W. |
| Předmět: |
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| Zdroj: |
Journal of Fish Biology; May2003, Vol. 62 Issue 5, p1044, 9p |
| Abstrakt: |
Carbon dioxide transport in African lungfish Protopterus aethiopicus blood conformed to the typical vertebrate scheme, implying a crucial and rate-limiting role of erythrocyte Cl[SUP-]/HCO[SUP-],[SUB3] exchange. The rate coefficient for unidirectional Cl[SUP-] efflux via the anion exchanger (k, s[SUP-1]) increased with temperature in African lungfish, but values were well below those reported in other species. The erythrocytes of African lungfish were, however, very large (mean cellular volume = 6940 μm[SUP3]), and the ratio of cell water volume to membrane surface area was high (V[SUBw]A[SUP-],[SUBm]=1.89). Hence, the apparent Cl[SUP-] permeability (P[SUBcl]= kV[SUBw]A[SUP-1],[SUBm], μms[SUP-1]) was close to that in other vertebrates. The plot of lnP[SUBCl] against the inverse absolute temperature was left-shifted in the tropical African lungfish compared to the temperate rainbow trout Oncorhynchus mykiss, which supports the idea that P[SUBCl] is similar among animals when compared at their preferred temperatures. Also, Q[SUB10] for anion exchange calculated from P[SUBCl] values in African lungfish was 230, supporting the idea that the temperature sensitivity of erythrocyte anion exchange matches the temperature sensitivity of CO[SUB2] production and transport in ectothermic vertebrates. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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