TY - JOUR
T1 - Effects of lithium on ionic composition and electrical properties of the lens
AU - Bentley, P. J.
AU - Candia, Oscar A.
N1 - Funding Information:
This work was supported by NIH grant EY cal assistance of Miss Elizabeth Cruz.
PY - 1977/11
Y1 - 1977/11
N2 - When the sodium in the external media bathing the amphibian crystalline lens is replaced by Li this ion enters the lens and displaces an equivalent amount of Na plus K. The organic cation choline behaved similarly to Li, in displacing Na and K. Li accumulation by the lens was reduced by ouabain, an effect which is not consistent with it being significantly transported by an outwardly directed lenticular active Na pump. The effect does, however, suggest that a specific exchange of cellular Na and external Li is occurring, such as if external K were being displaced by the Li in the Na pump mechanism. Elevation of cellular Na levels, however, did not alter the rate of Li entry into the lens and it seems unlikely that significant specific exchange of Na Li or K Li is occurring. Li cannot replace Na in maintaining the translenticular SCC, which again indicates that it cannot be actively transported like Na. The electrical resistance of the anterior and posterior sides of the lens (reflecting their permeability to ions) was increased when the Na in the solutions bathing them was replaced by Li. A similar change was seen when choline was used as a substituting cation. Amphotericin B increases the Na permeability of the anterior, epithelial, side of the lens (as reflected by a decrease in translenticular PD, SCC and Na accumulation in the tissue) and Li, but not choline, can also enter through these drug-induced channels. The results suggest that the lenticular requirements for alkali metal cations are highly specific and that Li cannot substitute effectively for Na or K. This property is reflected in a lower permeability to Li and an inability for it to enter the a active Na transport process. The Na-channels created by amphotericin B are, however, accessible to Li and these are thus not comparable to those that are normally present in the tissue.
AB - When the sodium in the external media bathing the amphibian crystalline lens is replaced by Li this ion enters the lens and displaces an equivalent amount of Na plus K. The organic cation choline behaved similarly to Li, in displacing Na and K. Li accumulation by the lens was reduced by ouabain, an effect which is not consistent with it being significantly transported by an outwardly directed lenticular active Na pump. The effect does, however, suggest that a specific exchange of cellular Na and external Li is occurring, such as if external K were being displaced by the Li in the Na pump mechanism. Elevation of cellular Na levels, however, did not alter the rate of Li entry into the lens and it seems unlikely that significant specific exchange of Na Li or K Li is occurring. Li cannot replace Na in maintaining the translenticular SCC, which again indicates that it cannot be actively transported like Na. The electrical resistance of the anterior and posterior sides of the lens (reflecting their permeability to ions) was increased when the Na in the solutions bathing them was replaced by Li. A similar change was seen when choline was used as a substituting cation. Amphotericin B increases the Na permeability of the anterior, epithelial, side of the lens (as reflected by a decrease in translenticular PD, SCC and Na accumulation in the tissue) and Li, but not choline, can also enter through these drug-induced channels. The results suggest that the lenticular requirements for alkali metal cations are highly specific and that Li cannot substitute effectively for Na or K. This property is reflected in a lower permeability to Li and an inability for it to enter the a active Na transport process. The Na-channels created by amphotericin B are, however, accessible to Li and these are thus not comparable to those that are normally present in the tissue.
KW - amphotericin B
KW - epithelial membrane
KW - lens
KW - lithium
UR - http://www.scopus.com/inward/record.url?scp=0017700324&partnerID=8YFLogxK
U2 - 10.1016/0014-4835(77)90173-7
DO - 10.1016/0014-4835(77)90173-7
M3 - Article
C2 - 413723
AN - SCOPUS:0017700324
SN - 0014-4835
VL - 25
SP - 447
EP - 457
JO - Experimental Eye Research
JF - Experimental Eye Research
IS - 5
ER -