Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
, 6 (5), 673-677

Parallel in vivo Monitoring of pH in Gill Capillaries and Muscles of Fishes Using Microencapsulated Biomarkers


Parallel in vivo Monitoring of pH in Gill Capillaries and Muscles of Fishes Using Microencapsulated Biomarkers

Ekaterina Borvinskaya et al. Biol Open.


Tracking physiological parameters in different organs within the same organism simultaneously and in real time can provide an outstanding representation of the organism's physiological status. The state-of-the-art technique of using encapsulated fluorescent molecular probes (microencapsulated biomarkers) is a unique tool that can serve as a platform for the development of new methods to obtain in vivo physiological measurements and is applicable to a broad range of organisms. Here, we describe a novel technique to monitor the pH of blood inside the gill capillaries and interstitial fluid of muscles by using microencapsulated biomarkers in a zebrafish model. The functionality of the proposed technique is shown by the identification of acidification under anesthesia-induced coma and after death. The pH in muscles reacts to hypoxia faster than that in the gill bloodstream, which makes both parameters applicable as markers of either local or bodily reactions.

Keywords: Blood pH; Encapsulated fluorescent sensors; Interstitial pH; Microencapsulated biomarkers; Physiological measurements in vivo; Zebrafish.

Conflict of interest statement

Competing interestsThe authors declare no competing or financial interests.


Fig. 1.
Fig. 1.
Calibration of fluorescent microencapsulated biomarkers (MBMs), and visualisation of MBMs in fish for in vivo pH measurements. (A) Calibration curves of the prepared pH-sensitive MBMs in sodium phosphate buffers, in C. carpio plasma, and in zebrafish blood. Putative calibration curve for MBMs in zebrafish blood was obtained by shifting the curve for buffers to fit the measurement in extracted zebrafish blood. For all measurements, the mean±s.d. is depicted. (B) Size distribution of prepared MBMs. (C) Scheme of zebrafish showing specific places where pH was measured with fluorescent MBMs.
Fig. 2.
Fig. 2.
pH measurements in gill capillaries and interstitial fluid of muscles of fishes immediately after the injection of MBMs and at 100 and 200 min after the injections. Experiments were replicated three times; n=17 individuals; dead animals were excluded from the experiment after one measurement. Solid lines represent the median values. Dashed blue line shows the median pH of blood in gill capillaries of fish at normal state for all time points. *Indicates statistically significant difference from group of fish at normal state at the respective time point with P<0.05 (Dunn's test with Hommel's correction).
Fig. 3.
Fig. 3.
Comparison of pH values measured by MBMs in gill capillaries and muscles with pH measurements in extracted blood measured using a microelectrode. Performed 200 min after injection for part of animals in different physiological states; n=7 individuals.

Similar articles

See all similar articles

Cited by 3 articles


    1. Babaei F., Ramalingam R., Tavendale A., Liang Y., Yan L. S. K., Ajuh P., Cheng S. H. and Lam Y. W. (2013). Novel blood collection method allows plasma proteome analysis from single zebrafish. J. Proteome Res. 12, 1580-1590. 10.1021/pr3009226 - DOI - PubMed
    1. Bottenus D., Oh Y.-J., Han S. M. and Ivory C. F. (2009). Experimentally and theoretically observed native pH shifts in a nanochannel array. Lab. Chip 9, 219-231. 10.1039/B803278E - DOI - PMC - PubMed
    1. Cheung E., Chatterjee D. and Gerlai R. (2014). Subcutaneous dye injection for marking and identification of individual adult zebrafish (Danio rerio) in behavioral studies. Behav. Res. Methods 46, 619-624. 10.3758/s13428-013-0399-x - DOI - PubMed
    1. Evans D. H. and Claiborne J. B. (1997). The Physiology of Fishes. 2nd edn USA: CRC Press.
    1. Gurkov A., Shchapova E., Bedulina D., Baduev B., Borvinskaya E., Meglinski I. and Timofeyev M. (2016). Remote in vivo stress assessment of aquatic animals with microencapsulated biomarkers for environmental monitoring. Sci. Rep. 6, 36427 10.1038/srep36427 - DOI - PMC - PubMed

LinkOut - more resources