Distribution of sodium and potassium within cattle lens

Sodium-23 and potassium-39 nuclear magnetic resonance relaxation in eye lens. Examples of quadrupole ion magnetic relaxation in a crowded protein environment

“…In addition, these studies revealed the presence of a small fraction (-0.02) of nondiffusible, i.e., nonexchangeable sodium. The conclusions of the present NMR study, namely the occurrence of a predominantly "free" and mobile ion population, and the likelihood of at least some NMR invisible ionic populations, is in agreement with the interpretation of an essentially "free" and mobile state for lens sodium and potassium offered by Duncan and van Heyningen (21,54). However, the small fraction of nondiffusible sodium detected in these studies (21) should not be confused with the small fraction of rapidly exchanging "bound" ion contributing to the NMR spectral and relaxation behavior (discrete two-site model assumed).…”

Sodium-23 and potassium-39 nuclear magnetic resonance relaxation in eye lens. Examples of quadrupole ion magnetic relaxation in a crowded protein environment

“…In addition, these studies revealed the presence of a small fraction (-0.02) of nondiffusible, i.e., nonexchangeable sodium. The conclusions of the present NMR study, namely the occurrence of a predominantly "free" and mobile ion population, and the likelihood of at least some NMR invisible ionic populations, is in agreement with the interpretation of an essentially "free" and mobile state for lens sodium and potassium offered by Duncan and van Heyningen (21,54). However, the small fraction of nondiffusible sodium detected in these studies (21) should not be confused with the small fraction of rapidly exchanging "bound" ion contributing to the NMR spectral and relaxation behavior (discrete two-site model assumed).…”

Sodium, Potassium and Calcium Contents of Bovine Lenses in Dependence on Age

“…Taking 65% as an average value for water content of the bovine lens [Paterson, 1969;Amoore et al, 1963], the K+ and N a+ data as well as the K+/Na+ ratio agree well with the data in the literature. The potassium/ calcium ratio is found at about half the value quoted by D uncan and van Heyningen [1976], This is no discrepancy since we have calculated on the basis of microequivalents in contrast to millimoles as used by the afore mentioned authors.…”

The role of macromolecular crowding in the evolution of lens crystallins with high molecular refractive index

“…In human, the crystallin concentration was estimated to be ~ 440 mg/ml, based on the results from Raman microspectroscopy [82], in agreement with a peak refractive index of 1.42 [83]. In rabbit, nuclear concentrations of ~500 mg/ml were measured [82], and slightly higher values can be estimated from the observed water content in the nucleus of calf lenses [81]. In this concentration range, due to the large fraction of excluded volume, small differences in protein concentration are nonlinearly amplified into large differences in the ‘effective concentrations’.…”

Sodium-23 and potassium-39 nuclear magnetic resonance relaxation in eye lens. Examples of quadrupole ion magnetic relaxation in a crowded protein environment

“…In addition, these studies revealed the presence of a small fraction (-0.02) of nondiffusible, i.e., nonexchangeable sodium. The conclusions of the present NMR study, namely the occurrence of a predominantly "free" and mobile ion population, and the likelihood of at least some NMR invisible ionic populations, is in agreement with the interpretation of an essentially "free" and mobile state for lens sodium and potassium offered by Duncan and van Heyningen (21,54). However, the small fraction of nondiffusible sodium detected in these studies (21) should not be confused with the small fraction of rapidly exchanging "bound" ion contributing to the NMR spectral and relaxation behavior (discrete two-site model assumed).…”

Sodium, Potassium and Calcium Contents of Bovine Lenses in Dependence on Age

“…Taking 65% as an average value for water content of the bovine lens [Paterson, 1969;Amoore et al, 1963], the K+ and N a+ data as well as the K+/Na+ ratio agree well with the data in the literature. The potassium/ calcium ratio is found at about half the value quoted by D uncan and van Heyningen [1976], This is no discrepancy since we have calculated on the basis of microequivalents in contrast to millimoles as used by the afore mentioned authors.…”

The role of macromolecular crowding in the evolution of lens crystallins with high molecular refractive index

“…In human, the crystallin concentration was estimated to be ~ 440 mg/ml, based on the results from Raman microspectroscopy [82], in agreement with a peak refractive index of 1.42 [83]. In rabbit, nuclear concentrations of ~500 mg/ml were measured [82], and slightly higher values can be estimated from the observed water content in the nucleus of calf lenses [81]. In this concentration range, due to the large fraction of excluded volume, small differences in protein concentration are nonlinearly amplified into large differences in the ‘effective concentrations’.…”

Sodium-23 and potassium-39 nuclear magnetic resonance relaxation in eye lens. Examples of quadrupole ion magnetic relaxation in a crowded protein environment

“…In addition, these studies revealed the presence of a small fraction (-0.02) of nondiffusible, i.e., nonexchangeable sodium. The conclusions of the present NMR study, namely the occurrence of a predominantly "free" and mobile ion population, and the likelihood of at least some NMR invisible ionic populations, is in agreement with the interpretation of an essentially "free" and mobile state for lens sodium and potassium offered by Duncan and van Heyningen (21,54). However, the small fraction of nondiffusible sodium detected in these studies (21) should not be confused with the small fraction of rapidly exchanging "bound" ion contributing to the NMR spectral and relaxation behavior (discrete two-site model assumed).…”

Sodium, Potassium and Calcium Contents of Bovine Lenses in Dependence on Age

“…Taking 65% as an average value for water content of the bovine lens [Paterson, 1969;Amoore et al, 1963], the K+ and N a+ data as well as the K+/Na+ ratio agree well with the data in the literature. The potassium/ calcium ratio is found at about half the value quoted by D uncan and van Heyningen [1976], This is no discrepancy since we have calculated on the basis of microequivalents in contrast to millimoles as used by the afore mentioned authors.…”

The role of macromolecular crowding in the evolution of lens crystallins with high molecular refractive index

“…In human, the crystallin concentration was estimated to be ~ 440 mg/ml, based on the results from Raman microspectroscopy [82], in agreement with a peak refractive index of 1.42 [83]. In rabbit, nuclear concentrations of ~500 mg/ml were measured [82], and slightly higher values can be estimated from the observed water content in the nucleus of calf lenses [81]. In this concentration range, due to the large fraction of excluded volume, small differences in protein concentration are nonlinearly amplified into large differences in the ‘effective concentrations’.…”