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A Journal on Cardiac, Vascular and Thoracic Surgery

Indexed/Abstracted in: BIOSIS Previews, Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index Expanded (SciSearch), Scopus
Impact Factor 1,632

Frequency: Bi-Monthly

ISSN 0021-9509

Online ISSN 1827-191X


The Journal of Cardiovascular Surgery 2001 August;42(4):475-80



pH paradox and neonatal heart

Baron O., Saiki Y., Rebeyka I. M.

From ­the Cardiovascular Research Group 261 C Heritage Medical Research Center Edmonton, Alberta, Canada

Background. To eval­u­ate ­the func­tion­al stat­us of ­the Na+/H+ exchang­er in ­the neo­na­tal ­heart.
Methods. On ­the Langendorff ­system, iso­lat­ed neo­na­tal rab­bit ­hearts ­were arrest­ed by ­using car­di­o­ple­gia ­with or with­out a spe­cif­ic Na+/H+ exchang­er block­er, 5-(N,N dime­thyl) amil­o­ride (­DMA) (20µM). Ischemic peri­od ­was 40 min­utes at 37°C or 120 min­utes at 20°C ­before 30 min­utes of reper­fu­sion at 37°C. When ­DMA ­was add­ed to ­the car­di­o­ple­gia solu­tion, it ­was ­also add­ed to ­the reper­fu­sate ­for ­the ­first 5 min­utes of reper­fu­sion (20 µM).
Results. Postischemic devel­oped pres­sure ­was 50.3±7.1 mmHg in ­the ­DMA ­group ver­sus 25.9±6 mmHg in ­the con­trol ­group (p<0.05) at 37°C ­and 74.8±14.6 mmHg in ­the ­DMA ­group ver­sus 60.6±11.5 mmHg in ­the con­trol ­group (p<0.05) at 20°C. Postischeimic dia­stol­ic pres­sure ­was 40.4±3.3 mmHg in ­the ­DMA ­group ver­sus 28.4±7 mmHg in ­the con­trol ­group (p<0.05) at 37°C ­and 9.6±3.1 mmHg in ­the ­DMA ­group ver­sus 15±3.7 in ­the con­trol ­group (p<0.05) at 20°C. Creatine ­kinase wash­out ­was 296±97 IU/L in ­the ­DMA ­group ver­sus 1253±537 IU/L in ­the con­trol ­group (p<0.05) at 37°C ­and 370±156 IU/L in ­the ­DMA ­group ver­sus 524±104 IU/L in ­the con­trol ­group (p<0.05) at 20°C.
Conclusions. 1) The Na+/H+ exchang­er is ­active in ­the neo­na­tal ­heart. 2) The Na+/H+ exchang­er ­plays a ­key-­role in ­the path­o­gen­e­sis of reper­fu­sion inju­ry of ­the neo­na­tal myo­car­di­um. 3) This exchang­er is sen­si­tive ­even ­for ­low H+ trans­mem­brane gra­dients ­and ­even ­under hypo­ther­mic con­di­tions.

language: English

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