Table 2.

Effects of urethane–xylazine anesthesia after a 20-min baseline (0 min) period

	Time (min)
	0	1–20	21–40	41–60	61–80	81–100	101–120	121–140	141–160	161–180	181–200	201–220	221–240	241–260	261–280	281–300
P1 latency
O2	1253 ± 91	1249 ± 86	1245 ± 89	1244 ± 90	1240 ± 90	1245 ± 85	1243 ± 78	1242 ± 78	1248 ± 78	1247 ± 79	1247 ± 81	1245 ± 81	1249 ± 87	1262 ± 95a	1261 ± 92a	1258 ± 89a
No O2	1274 ± 34	1287 ± 38	1283 ± 41	1277 ± 37	1275 ± 38	1275 ± 38	1279 ± 48	1275 ± 41	1288 ± 35	1300 ± 42	1299 ± 25	1293 ± 22	1297 ± 26	1280 ± 30b	1278 ± 36b	1275 ± 35b
N1 latency
O2	1551± 101	1540 ± 97	1532 ± 95	1524 ± 100	1523 ± 99	1525 ± 93	1524 ± 93	1526 ± 82	1529 ± 83	1527 ± 80	1523 ± 84	1531 ± 81	1529 ± 84	1533 ± 90a	1538 ± 94a	1537 ± 98a
No O2	1553 ± 47	1552 ± 45	1545 ± 40	1544 ± 37	1542 ± 40	1549 ± 49	1555 ± 64	1549 ± 35	1564 ± 39	1570 ± 36	1562 ± 25	1568 ± 32	1563 ± 27	1569 ± 33b	1570 ± 39b	1563 ± 33b
P2 latency
O2	1932 ± 92	1915 ± 87	1918 ± 86	1906 ± 85	1903 ± 92	1898 ± 92	1893 ± 97	1900 ± 84	1901 ± 80	1903 ± 82	1896 ± 84	1886 ± 82	1889 ± 89	1907 ± 84a	1905 ± 96a	1904 ± 94a
No O2	1935 ± 41	1930 ± 36	1925 ± 26	1925 ± 43	1921 ± 41	1925 ± 49	1920 ± 41	1918 ± 36	1919 ± 29	1921 ± 29	1913 ± 29	1915 ± 24	1911 ± 28	1913 ± 35b	1906 ± 35b	1893 ± 9b
P1–N1 amplitude
O2	1.10 ±0.27	1.11 ±0.26	1.14 ± 0.28	1.14 ± 0.27	1.15 ±0.24	1.17 ± 0.30	1.13 ± 0.28	1.15 ± 0.28	1.18 ± 0.26	1.14 ± 0.32	1.19 ± 0.29	1.17 ± 0.30	1.14 ± 0.30	1.00 ± 0.07a	1.06 ± 0.10a	1.07 ± 0.10a
No O2	0.97 ±0.30	0.97 ±0.25	0.96 ± 0.30	0.94 ± 0.34	0.95 ±0.34	0.95 ± 0.38	0.95 ± 0.36	0.95 ± 0.34	0.96 ± 0.30	0.89 ± 0.31	0.88 ± 0.32	0.91 ± 0.32	0.95 ± 0.38	0.79 ± 0.18b	0.85 ± 0.26b	0.84 ± 0.25b
P2–N1 amplitude
O2	0.94 ±0.40	0.97 ±0.42	1.06 ± 0.35	1.00 ± 0.36	1.01 ±0.33	0.99 ± 0.31	1.02 ± 0.38	1.02 ± 0.38	0.97 ± 0.37	0.94 ± 0.33	0.90 ± 0.30	0.85 ± 0.32	0.85 ± 0.26	0.82 ± 0.20a	0.83 ± 0.18a	0.84 ± 0.18a
No O2	0.91 ±0.42	0.93 ±0.43	0.91 ± 0.40	0.92 ± 0.36	0.89 ±0.39	0.85 ± 0.47	0.83 ± 0.46	0.85 ± 0.41	0.82 ± 0.37	0.75 ± 0.35	0.72 ± 0.31	0.71 ± 0.31	0.71 ± 0.30	0.61 ± 0.24b	0.60 ± 0.29b	0.65 ± 0.34b
Threshold
O2	−10.5 ± 0.0	−11.0 ± 1.2	−10.5 ± 0.0	−10.5 ± 0.0	−10.5 ± 1.9	−10.0 ± 1.2	−10.0 ± 1.2	−10.5 ± 1.9	−9.5 ± 1.6	−10.5 ± 0.0	−10.0 ± 1.2	−11.5 ± 1.6	−10.0 ± 1.2	−9.9 ± 1.3a	−10.5 ± 0.0a	−10.5 ± 0.0a
No O2	−9.5 ± 1.6	−11.0 ± 2.3	−10.5 ± 0.0	−9.5 ± 1.6	−11.0 ± 2.3	−10.5 ± 2.7	−8.5 ± 1.6	−8.5 ± 1.6	−10.0 ± 1.2	−9.5 ± 1.6	−10.0 ± 2.3	−10.0 ± 1.2	−10.0 ± 1.2	−12.0 ± 1.7b	−12.0 ± 1.7b	−11.3 ± 1.5b

VsEP latencies (µs) and amplitudes (µV) obtained at +6dB and 1.0 g/ms and response thresholds over time are shown. Results from O₂-supplemented and nonsupplemented groups under urethane–xylazine anesthesia are represented. Each time period was characterized by averaging 4 or 5 consecutive measurements at approximately 5-min intervals. Brain temperature was controlled at 36.0 ± 0.2 °C, and rectal temperatures were maintained at 37.0 ± 0.2 °C in all animals. Data are shown as mean ± 1 SD of 6 animals, except where noted. Sample size decreased after 240 minutes because some animals were euthanized.

^an = 5.

^bn = 4.