42 HIGH SPIN-SPIN RELAXATION TIMES SEEN BY PROTON MAGNETIC RESONANCE SPECTROSCOPY IN PIGLET BRAINS CORRELATE WITH ATP DEPLETION AFTER ACUTE HYPOXIA-ISCHAEMIA

Abstract

Using ¹H and ³¹P magnetic resonance spectroscopy (MRS) we aimed to investigate relationships between ¹H spin-spin relaxation times (T₂s) and nucleotide triphosphate (NTP; largely ATP) levels in newborn piglet brains after acute hypoxia-ischaemia. Six newborn piglets had bilateral common-carotid occlusion and hypoxaemia for ≤ 1.5 hr followed by reperfusion and normal oxygenation. NTP levels were defined relative to the exchangeable ³¹P pool (EPP = inorganic phosphate + phosphocreatine (PCr) + (γ + α + β)-NTP). Control T₂s (mean (SD)) of choline (Cho), creatine + PCr (Cr), and N-acetylaspartate (Naa) were 255 (50), 160 (23), and 215 (34) ms respectively; NTP/EPP was 0.21 (.01). During the insult, Cr T₂ rose to 263 (51) ms (p<.0002; paired t-test) as NTP/EPP fell to 0.05 (.05) (p<.0005). An hour after resuscitation, both NTP/EPP and Cr T₂ reverted to control values. In 3 piglets, studies continued for up to 50 hr. NTP/EPP fell as secondary energy failure (SEF) developed and the Cho, Cr, and Naa T₂s rose linearly to 520 (p<.02), 620 (p<.001), and 590 (p<.001) ms respectively. The increased T₂s during the development of SEF were probably due to failure of the ATP-dependcnt Na⁺/K⁺ pump indicating their value as indices of cellular oedema following birth asphyxia.

Log in or create a free account to read this content

Gain free access to this article, as well as selected content from this journal and more on nature.com

Access through your institution

or

Sign in or create an account

Continue with Google

Continue with ORCiD