Direct visualization of hemolymph flow in the heart of a grasshopper (Schistocerca americana)

Wah-Keat Lee,John J Socha

doi:10.1186/1472-6793-9-2

Wah-Keat Lee, John J Socha

Open Access

https://doi.org/10.1186/1472-6793-9-2

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Journal: BMC Physiology	Publication Date: Jan 1, 2009
Citations: 55	License type: cc-by

Affiliation: Argonne National Laboratory, Virginia Tech

Abstract

BackgroundHemolymph flow patterns in opaque insects have never been directly visualized due to the lack of an appropriate imaging technique. The required spatial and temporal resolutions, together with the lack of contrast between the hemolymph and the surrounding soft tissue, are major challenges. Previously, indirect techniques have been used to infer insect heart motion and hemolymph flow, but such methods fail to reveal fine-scale kinematics of heartbeat and details of intra-heart flow patterns.ResultsWith the use of microbubbles as high contrast tracer particles, we directly visualized hemolymph flow in a grasshopper (Schistocerca americana) using synchrotron x-ray phase-contrast imaging. In-vivo intra-heart flow patterns and the relationship between respiratory (tracheae and air sacs) and circulatory (heart) systems were directly observed for the first time.ConclusionSynchrotron x-ray phase contrast imaging is the only generally applicable technique that has the necessary spatial, temporal resolutions and sensitivity to directly visualize heart dynamics and flow patterns inside opaque animals. This technique has the potential to illuminate many long-standing questions regarding small animal circulation, encompassing topics such as retrograde heart flow in some insects and the development of flow in embryonic vertebrates.

Highlights

Hemolymph flow patterns in opaque insects have never been directly visualized due to the lack of an appropriate imaging technique
Microbubbles ranging from 10–150 μm in diameter were clearly visualized, as were air sacs and numerous tracheae, including a main longitudinal tracheal trunk that runs adjacent to the heart (Fig. 1C and Additional files 1, 2, 3, 4, 5, 6 and 7)
The buoyant bubbles accumulated along the ventral edge of the dorsal diaphragm, which partially compartmentalizes the dorsal heart region

Summary

Introduction

Hemolymph flow patterns in opaque insects have never been directly visualized due to the lack of an appropriate imaging technique. Real-time synchrotron x-ray phase-contrast imaging [2] has recently been demonstrated to be an excellent technique for the study of respiratory and digestive systems in small animals, and it has the necessary resolution to study blood flow as well. This technique is capable of spatial and temporal resolutions of ~1 μm and ~100 ps, respectively, these parameters have to (page number not for citation purposes)

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