Antibodies against the cardiac sodium/bicarbonate co-transporter (NBCe1) as pharmacological tools
Background and purpose: Na⁺/HCO<sub>3</sub>⁻ co-transport (NBC) regulates intracellular pH (pH<sub>i</sub>) in the heart. We have studied the electrogenic NBC isoform NBCe1 by examining the effect of functional antibodies to this protein. Experimental approach: We generated...
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| Autores principales: | , , , , , , |
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| Formato: | Articulo |
| Lenguaje: | Inglés |
| Publicado: |
2011
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| Materias: | |
| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/97962 https://ri.conicet.gov.ar/11336/61760 https://bpspubs.onlinelibrary.wiley.com/doi/abs/10.1111/j.1476-5381.2011.01496.x |
| Aporte de: |
| Sumario: | Background and purpose: Na⁺/HCO<sub>3</sub>⁻ co-transport (NBC) regulates intracellular pH (pH<sub>i</sub>) in the heart. We have studied the electrogenic NBC isoform NBCe1 by examining the effect of functional antibodies to this protein.
Experimental approach: We generated two antibodies against putative extracellular loop domains 3 (a-L3) and 4 (a-L4) of NBCe1 which recognized NBCe1 on immunoblots and immunostaining experiments. pH<sub>i</sub> was monitored using epi-fluorescence measurements in cat ventricular myocytes. Transport activity of total NBC and of NBCe1 in isolation were evaluated after an ammonium ion-induced acidosis (expressed as H⁺ flux, J<sub>H</sub>, in mmol·L<sup>-1</sup> min<sup>-1</sup> at pH<sub>i</sub> 6.8) and during membrane depolarization with high extracellular potassium (potassium pulse, expressed as ΔpH<sub>i</sub>) respectively.
Key results: The potassium pulse produced a pH<sub>i</sub> increase of 0.18 ± 0.006 (n= 5), which was reduced by the a-L3 antibody (0.016 ± 0.019). The a-L-3 also decreased J<sub>H</sub> by 50%. Surprisingly, during the potassium pulse, a-L4 induced a higher pH<sub>i</sub> increase than control,(0.25 ± 0.018) whereas the recovery of pH<sub>i</sub> from acidosis was faster (J<sub>H</sub> was almost double the control value). In perforated-patch experiments, a-L3 prolonged and a-L4 shortened action potential duration, consistent with blockade and stimulation of NBCe1-carried anionic current respectively.
Conclusions and implications: Both antibodies recognized NBCe1, but they had opposing effects on the function of this transporter, as the a-L3 was inhibitory and the a-L4 was excitatory. These antibodies could be valuable in studies on the pathophysiology of NBCe1 in cardiac tissue, opening a path for their potential clinical use. |
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