TABLE 1.

Effects of Protons and HZE Particles on Glutamate Uptake in Astrocytes and Neurons

Cell type	Radiation type	Dose-averaged LET (keV/μm)	Dose	Fluence (particles/cm2)	Average hits/cell	Glutamate uptakea at 3 h	Glutamate uptakea at 2 days	Glutamate uptakea at 7 days
Astrocytes	Gamma raysb (1.17  and 1.33 MeV)	0.25	10 cGy	n/a	n/a	–	–	–
			50 cGy	n/a	n/a	decreased	–	–
			2 Gy	n/a	n/a	decreased	–	–
	Protons (250 MeV)	0.4	10 cGy	1.6 × 108	11,098	decreased	–	–
			50 cGy	7.8 × 108	55,494	decreased	decreased	–
			2 Gy	3.1 × 109	221,976	decreased	–	–
	Carbon ions (290 MeV/  nucleon)	13	10 cGy	4.8 × 106	342	decreased	–	decreased
			50 cGy	2.4 × 107	1708	decreased	–	decreased
			2 Gy	9.6 × 107	6830	decreased	decreased	decreased
	Iron ions (1000 MeV/  nucleon)	148	10 cGy	4.2 × 105	30	–	decreased	decreased
			50 cGy	2.1 × 106	150	–	decreased	decreased
			2 Gy	8.4 × 106	600	–	decreased	–
Neurons	Gamma rays (1.17 and  1.33 MeV)	0.25	10 cGy	2.5 × 108	445	increased	–	–
			50 cGy	1.2 × 109	2224	increased	increased	increased
			2 Gy	5.0 × 109	8895	increased	increased	increased
	Protons (250 MeV)	0.4	10 cGy	1.6 × 108	278	increased	increased	–
			50 cGy	7.8 × 108	1390	increased	increased	increased
			2 Gy	3.1 × 109	5560	increased	increased	increased
	Carbon ions (290 MeV/  nucleon)	13	10 cGy	4.8 × 106	9	increased	increased	increased
			50 cGy	2.4 × 107	43	increased	–	–
			2 Gy	9.6 × 107	171	increased	–	–
	Iron ions (1000 MeV/  nucleon)	148	10 cGy	4.2 × 105	1	–	increased	–
			50 cGy	2.1 × 106	4	increased	increased	increased
			2 Gy	8.4 × 106	15	increased	increased	increased

^aDashes indicate that there was no significant change in uptake after irradiation.

^bLET based on microdosimetry electron spectra.