Table 3.

Summary of experiments conducted that assess influence of extracellular and particulate factors on Ni particulate uptake

Extracellular Factors	Conditions	Relationship to uptake	Study
Media	Salts/Glucose Media Complex Culture Media fortified with 10% FBS	No effect	Heck and Costa, 1982a
Temperature	37°C-high temperature 4°C-low temperature	Lower temperatures decrease uptake for NiS, may be related to decrease in cell metabolism	Heck and Costa, 1982a
Calcium	Calmodulin antagonist Calcium removed from media	Significant reduction in uptake for amorphous NiS and crystalline Ni3S2	Heck and Costa, 1982a
Presence of Other Metals	Mn dust Mn2+ ions Amorphous NiS	Significant reduction in uptake for crystalline Ni3S2 in all cases	Costa et. al., 1981b
Dansylcadaverine	0, 25, 50, 60, 75, 100 μm	Significant reduction in uptake for crystalline Ni3S2 at all concentrations	Costa et. al., 1981a
Actinomycin D	0.1, 1.0, 4.0 μg/mL	Significant reduction in uptake for crystalline Ni3S2 at all concentrations	Costa et. al., 1981a
Cycloheximide	1.0, 5.0, 20.0 μg/mL	Significant reduction in uptake for crystalline Ni3S2 at all concentrations	Costa et. al., 1981a
Particulate Factors
Mean Particle Diameter	1.8 μm 4.0 μm 5.0 μm >5.0 μm	<4 μm: actively endocytized 4-5 μm: reduced endocytosis relative to <4 μm >5 μm: not actively endocytized	Costa et. al., 1981a
Structure	Crystalline Form Amorphous Form	Crystalline forms are actively endocytized and amorphous forms are not	Costa et al, 1982a
Charge	Chemical reduction via LiAlH4 for crystalline and amorphous forms	Increased uptake	Heck and Costa, 1982c
Surface properties	Solvent cleaning and storage in inert atmosphere	Increased uptake	Heck and Costa, 1982c
Ni-S ratio on surface	Crystalline NiS had more nickel atoms on surface relative to amorphous NiS	Unknown	Abbracchio et al, 1981
Primary sulfur oxidation state	Crystalline NiS: Ni − 2 Amorphous NiS: Ni+6	Unknown	Abbracchio et al, 1981
	Primary oxidation state not affected by charge reduction with LiAlH4