Neutralized Lanthanum Solution a Largely Noncolloidal Ultrastructural Tracer

Abstract

Lanthanum nitrate solution adjusted to pH 7.4 and pH 7.7 was subjected to column chromatography, ultrafiltration and conductivity measurements. Lanthanum concentration was measured by a colorimetric method employing eriochrome cyanine RC. Under these conditions, lanthanum was not excluded from the column by a packing with an exclusion limit of 1800 daltons. Ultrafiltration through a membrane with a filter limit of 500 daltons allowed approximately 75% of the lanthanum to pass. Conductivity measurements showed a decrease of charge of about 20% on adding sodium hydroxide to a solution of lanthanum nitrate up to a pH of 7.7. It is concluded that approximately 80% of the lanthanum exists as a charged particle of less than 500 daltons at pH 7.7; the other 20% consists of larger, possibly colloidal particles. Nonfiltered and ultrafiltered lanthanum have equally good staining and tracer properties in the electron microscope, suggesting that staining depends largely on the ultrafiltrable noncolloidal lanthanum ion.

Lanthanum probing of cell membrane permeability in the rat heart: Pathological versus artefactual alterations

“…The similarity between ionic and "colloidal" lanthanum may partly be explained by the presence of a con-siderable proportion of ionic and transitional species in the sol (Schatzki and Newsome, 1975). However, in contrast to our findings, other researchers, using the same lanthanum colloid technique have reported exclusion of the probe by normal myocardial tissue (Fahimi and Cotran, 1971;Hawkins et al, 1978;Hoffstein et al, 1975;Revel and Karnovsky, 1967).…”

“…These particles are amongst the smallest colloidal tracers known (Hayat, 1975). However, the sol is stabilized by cations and small charged complexes (Schatzki and Newsome, 1975) and hence the solution is not a pure colloid. These characteristics of size and binding, together with the marked ease of detection of lanthanum with the electron microscope, have been exploited extensively to demonstrate membrane and interstitial continuities in a variety of tissues (Shaklai and Tavassoli, 1982).…”

Structural basis of neuron-to-neuron cross-excitation in dorsal root ganglia

“…If this is so, the satellite cell-satellite cell seam and the neuronsatellite cell cleft in vivo must be patent enough to provide rapid and unobstructed diffusional access to the much smaller neurotransmitter molecules which are candidate mediators of cell-to-cell communication in DRGs. More recently, however, Schatzki and Newsome (1975) have presented evidence to the effect that La 3+ in fact diffuses in its ionic form (or at least in a form that passes ultrafiltration with an upper cutoff of 500 Daltons), only to polymerize into electron-dense crystals in situ. This presents a potential problem~ It is easy to see how access by colloidal La(OH)3 could be reduced if chemical denaturation, or the formation of crossbridges during fixation, constricted the seam and cleft pathways from their normal diameter in the hydrated state.…”

Cell-Matrix Interrelation and Cell-to-Cell Connection in the Secretory Ameloblast Layer of Kitten Teeth

“…Though Takano and Crenshaw [1980] have not shown the pH of perfused lanthanum solution, the colloidal and ionic forms of lanthanum are in a state of equilib rium that is pH-dependent, and at a pH between 7.4 and 7.8. more than 70% lanthanum is ionized [Shaklai and Tavassoli, 1982]. Schatzki and Newsome [1975] have in dicated that in lanthanum nitrate solution at pH 7.7 ap proximately 80% of lanthanum exists as charged parti cles. Therefore, if the trivalent lanthanum cation penet rating the interameloblast spaces occurs in ionized form, the ionic resistance of the narrow intercellular spaces at the distal tight junctions and surface charge of the cells may be related with the loss of permeability to lanth anum [Tice et al.…”