Contribution of Na+/H+ exchange to pH regulation in pulmonary artery smooth muscle cells
Related Experiment Video
Updated: Aug 12, 2026

Isolation of Pulmonary Artery Smooth Muscle Cells from Neonatal Mice
Published on: October 20, 2013
D A Quinn1, T W Honeyman, P M Joseph
1Department of Physiology, University of Massachusetts Medical School, Worcester 01655.
Abstract:
In blood vessels in the systemic circulation, the plasmalemmal Na+/H+ exchanger has been implicated in a variety of cellular functions, including the regulation of intracellular pH (pHi) and cell volume, and the response to smooth muscle mitogens. The role of this transport system in pulmonary vascular smooth muscle has not been explored. The present study examined the characteristics of Na+/H+ exchange in cultured guinea pig pulmonary artery smooth muscle cells. These cells were subjected to an acid load, and the recovery from acid loading was monitored using the fluorescent pH-sensitive dye 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF). In the absence of HCO3-, pHi recovery from acid loading was dependent on external Na+ and was inhibited by the Na+/H+ exchange inhibitor dimethylamiloride (DMA) (recovery rate was reduced from 54.4 +/- 5.5 to 12.8 +/- 2.0 mmol H+/liter.min). This exchanger was also active in the presence of HCO3-; DMA reduced resting pHi and slowed the rate of recovery from acid loading in HCO3- buffers. However, in the presence of HCO3-, other transport systems, presumably HCO3-/Cl- exchange, also contribute to the regulation of pHi. In HCO3- buffers, the rate of recovery from acid load averaged 40.8 +/- 1.8 mmol H+/liter.min. Addition of 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), an inhibitor of HCO3-/Cl- exchange, slowed this recovery to 25.5 +/- 1.6 mmol H+/liter.min. A combination of DIDS and DMA further slowed the recovery to 19.7 +/- 1.5 mmol H+/liter.min. These findings indicate that the Na+/H+ exchanger plays a significant role in the regulation of pHi in pulmonary artery smooth muscle cells, even in HCO(3-)-containing buffers.
Related Concept Videos
Nitric Oxide Signaling Pathway
pH Homeostasis
Respiratory Regulation of...
Transducer Mechanism: Enzyme-Linked Receptors
Major types that are helpful drug targets include:
Adrenergic Neurons: Neurotransmission
Synthesis: Catecholamine synthesis requires tyrosine, which is taken...
Autoregulation of Blood Flow
Chemical Signaling in Autoregulation
Chemical signaling operates at the precapillary sphincter level, inciting either contraction or relaxation.
Respiratory Regulation of Acid-Base Balance
When carbon dioxide levels increase in the blood, more H+ and HCO3⁻ are produced, leading to a...

