Abstract
In this study, we test the hypothesis that in newborn hearts (as in adults) hypoxia and acidification stimulate increased Na+ uptake, in part via pH-regulatory Na+/H+ exchange. Resulting increases in intracellular Na+ (Nai) alter the force driving the Na+/Ca2+ exchanger and lead to increased intracellular Ca2+. NMR spectroscopy measured Nai and cytosolic Ca2+ concentration ([Ca2+]i) and pH (pHi) in isolated, Langendorff-perfused 4- to 7-day-old rabbit hearts. After Na+/K+ ATPase inhibition, hypoxic hearts gained Na+, whereas normoxic controls did not [19 ± 3.4 to 139 ± 14.6 vs. 22 ± 1.9 to 22 ± 2.5 (SE) meq/kg dry wt, respectively]. In normoxic hearts acidified using the NH4Cl prepulse, pHi fell rapidly and recovered, whereas Nai rose from 31 ± 18.2 to 117.7 ± 20.5 meq/kg dry wt. Both protocols caused increases in [Ca]i; however, [Ca]i increased less in newborn hearts than in adults (P < 0.05). Increases in Nai and [Ca]i were inhibited by the Na+/H+ exchange inhibitormethylisobutylamiloride (MIA, 40 μM; P < 0.05), as well as by increasing perfusate osmolarity (+30 mosM) immediately before and during hypoxia (P < 0.05). The data support the hypothesis that in newborn hearts, like adults, increases in Nai and [Ca]i during hypoxia and after normoxic acidification are in large part the result of increased uptake via Na+/H+ and Na+/Ca2+ exchange, respectively. However, for similar hypoxia and acidification protocols, this increase in [Ca]i is less in newborn than adult hearts.
| Original language | English (US) |
|---|---|
| Journal | American Journal of Physiology - Cell Physiology |
| Volume | 284 |
| Issue number | 5 53-5 |
| State | Published - May 1 2003 |
Fingerprint
Keywords
- Intracellular Na, Ca, and pH
- Newborn heart
ASJC Scopus subject areas
- Clinical Biochemistry
- Cell Biology
- Physiology
Cite this
Age-related differences in Na+-dependent Ca2+ accumulation in rabbit hearts exposed to hypoxia and acidification. / Anderson, S. E.; Liu, Hong; Ho, Hung S; Lewis, E. J.; Cala, Peter M.
In: American Journal of Physiology - Cell Physiology, Vol. 284, No. 5 53-5, 01.05.2003.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Age-related differences in Na+-dependent Ca2+ accumulation in rabbit hearts exposed to hypoxia and acidification
AU - Anderson, S. E.
AU - Liu, Hong
AU - Ho, Hung S
AU - Lewis, E. J.
AU - Cala, Peter M
PY - 2003/5/1
Y1 - 2003/5/1
N2 - In this study, we test the hypothesis that in newborn hearts (as in adults) hypoxia and acidification stimulate increased Na+ uptake, in part via pH-regulatory Na+/H+ exchange. Resulting increases in intracellular Na+ (Nai) alter the force driving the Na+/Ca2+ exchanger and lead to increased intracellular Ca2+. NMR spectroscopy measured Nai and cytosolic Ca2+ concentration ([Ca2+]i) and pH (pHi) in isolated, Langendorff-perfused 4- to 7-day-old rabbit hearts. After Na+/K+ ATPase inhibition, hypoxic hearts gained Na+, whereas normoxic controls did not [19 ± 3.4 to 139 ± 14.6 vs. 22 ± 1.9 to 22 ± 2.5 (SE) meq/kg dry wt, respectively]. In normoxic hearts acidified using the NH4Cl prepulse, pHi fell rapidly and recovered, whereas Nai rose from 31 ± 18.2 to 117.7 ± 20.5 meq/kg dry wt. Both protocols caused increases in [Ca]i; however, [Ca]i increased less in newborn hearts than in adults (P < 0.05). Increases in Nai and [Ca]i were inhibited by the Na+/H+ exchange inhibitormethylisobutylamiloride (MIA, 40 μM; P < 0.05), as well as by increasing perfusate osmolarity (+30 mosM) immediately before and during hypoxia (P < 0.05). The data support the hypothesis that in newborn hearts, like adults, increases in Nai and [Ca]i during hypoxia and after normoxic acidification are in large part the result of increased uptake via Na+/H+ and Na+/Ca2+ exchange, respectively. However, for similar hypoxia and acidification protocols, this increase in [Ca]i is less in newborn than adult hearts.
AB - In this study, we test the hypothesis that in newborn hearts (as in adults) hypoxia and acidification stimulate increased Na+ uptake, in part via pH-regulatory Na+/H+ exchange. Resulting increases in intracellular Na+ (Nai) alter the force driving the Na+/Ca2+ exchanger and lead to increased intracellular Ca2+. NMR spectroscopy measured Nai and cytosolic Ca2+ concentration ([Ca2+]i) and pH (pHi) in isolated, Langendorff-perfused 4- to 7-day-old rabbit hearts. After Na+/K+ ATPase inhibition, hypoxic hearts gained Na+, whereas normoxic controls did not [19 ± 3.4 to 139 ± 14.6 vs. 22 ± 1.9 to 22 ± 2.5 (SE) meq/kg dry wt, respectively]. In normoxic hearts acidified using the NH4Cl prepulse, pHi fell rapidly and recovered, whereas Nai rose from 31 ± 18.2 to 117.7 ± 20.5 meq/kg dry wt. Both protocols caused increases in [Ca]i; however, [Ca]i increased less in newborn hearts than in adults (P < 0.05). Increases in Nai and [Ca]i were inhibited by the Na+/H+ exchange inhibitormethylisobutylamiloride (MIA, 40 μM; P < 0.05), as well as by increasing perfusate osmolarity (+30 mosM) immediately before and during hypoxia (P < 0.05). The data support the hypothesis that in newborn hearts, like adults, increases in Nai and [Ca]i during hypoxia and after normoxic acidification are in large part the result of increased uptake via Na+/H+ and Na+/Ca2+ exchange, respectively. However, for similar hypoxia and acidification protocols, this increase in [Ca]i is less in newborn than adult hearts.
KW - Intracellular Na, Ca, and pH
KW - Newborn heart
UR - http://www.scopus.com/inward/record.url?scp=0037405693&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037405693&partnerID=8YFLogxK
M3 - Article
C2 - 12519744
AN - SCOPUS:0037405693
VL - 284
JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
SN - 1931-857X
IS - 5 53-5
ER -