Table 12. Nuclear Magnetic Resonance (³¹P-NMR)-Derived ATP Levels in Rat and Human Retinas under Normal and Hypoxic Conditions and Restoration of ATP with Two Different Drugs^a.

experiments/treatments	ATP and its phosphorus metabolites (% of control levels)
rat retinas	ATP	PCr	Pi
normal controls	98.4 ± 1.15	85.7 ± 2.3	95.0 ± 2.3
after 2.0 h hypoxia	48.1 ± 2.1***	nd	nd
after 1.0 h hypoxia	69.5 ± 3.46***	56.0 ± 4.6***	75.0 ± 8.6
after 1 h with MK-801 at 50 μM	97.4 ± 4.6***	102.0 ± 4.5***	89.3 ± 4.04
after 2 h with MK-801 at 50 μM	72.6 ± 1.4**	nd	nd
after 1 h with MK-801 at 5 nM	92.0 ± 1.4***	101.0 ± 5.7***	76.8 ± 3.57

human retinas	% of control ATP
normal controls	98 ± 12
after 2.0 h hypoxia	52 ± 8**
after 2 h with MK-801 at 50 μM	74 ± 6*
after 2 h with diltiazem at 50 μM	67 ± 4

^aEffect on tissue ATP and its metabolites after hypoxia/reperfusion of rat and human retinas in the absence and presence of MK-801 (NMDA-receptor-channel blocker) and diltiazem (Ca²⁺-channel blocker) as determined by ³¹P NMR spectroscopy. PCr = phosphocreatinin; P_i = inorganic phosphate; nd = not determined; *P < 0.05; **P < 0.02; ***P < 0.01. Data from ref (7).