Photoacoustic imaging of in vivo hemodynamic responses to sodium nitroprusside.


The in vivo hemodynamic impact of sodium nitroprusside (SNP), a widely used antihypertensive agent, has not been well studied. Here, we applied functional optical-resolution photoacoustic microscopy (OR-PAM) to study the hemodynamic responses to SNP in mice in vivo. As expected, after the application of SNP, the systemic blood pressure (BP) was reduced by 53%. The OR-PAM results show that SNP induced an arterial vasodilation of 24% and 23% in the brain and skin, respectively. A weaker venous vasodilation of 9% and 5% was also observed in the brain and skin, respectively. The results show two different types of blood oxygenation response. In mice with decreased blood oxygenation, the arterial and venous oxygenation was respectively reduced by 6% and 13% in the brain, as well as by 7% and 18% in the skin. In mice with increased blood oxygenation, arterial and venous oxygenation was raised by 4% and 22% in the brain, as well as by 1% and 9% in the skin. We observed venous change clearly lagged the arterial change in the skin, but not in the brain. Our results collectively show a correlation among SNP induced changes in systemic BP, vessel size and blood oxygenation.





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Publication Info

Zhang, Dong, Ran Li, Maomao Chen, Tri Vu, Huaxin Sheng, Wei Yang, Ulrike Hoffmann, Jianwen Luo, et al. (2021). Photoacoustic imaging of in vivo hemodynamic responses to sodium nitroprusside. Journal of biophotonics. p. e202000478. 10.1002/jbio.202000478 Retrieved from

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Huaxin Sheng

Associate Professor in Anesthesiology

We have successfully developed various rodent models of brain and spinal cord injuries in our lab, such as focal cerebral ischemia, global cerebral ischemia, head trauma, subarachnoid hemorrhage, intracerebral hemorrhage, spinal cord ischemia and compression injury. We also established cardiac arrest and hemorrhagic shock models for studying multiple organ dysfunction.  Our current studies focus on two projects. One is to examine the efficacy of catalytic antioxidant in treating cerebral ischemia and the other is to examine the efficacy of post-conditioning on outcome of subarachnoid hemorrhage induced cognitive dysfunction.


Wei Yang

Professor in Anesthesiology

Junjie Yao

Associate Professor of Biomedical Engineering

Our mission at PI-Lab is to develop state-of-the-art photoacoustic tomography (PAT) technologies and translate PAT advances into diagnostic and therapeutic applications, especially in functional brain imaging and early cancer theranostics. PAT is the most sensitive modality for imaging rich optical absorption contrast over a wide range of spatial scales at high speed, and is one of the fastest growing biomedical imaging technologies. Using numerous endogenous and exogenous contrasts, PAT can provide high-resolution images at scales covering organelles, cells, tissues, organs, small-animal organisms, up to humans, and can reveal tissue’s anatomical, functional, metabolic, and even histologic properties, with molecular and neuronal specificity.

At PI-Lab, we develop PAT technologies with novel and advanced imaging performance, in terms of spatial resolutions, imaging speed, penetration depth, detection sensitivity, and functionality. We are interested with all aspects of PAT technology innovations, including efficient light illumination, high-sensitivity ultrasonic detection, super-resolution PAT, high-speed imaging acquisition, novel PA genetic contrast, and precise image reconstruction. On top of the technological advancements, we are devoted to serve the broad life science and medical communities with matching PAT systems for various research and clinical needs. With its unique contrast mechanism, high scalability, and inherent functional and molecular imaging capabilities, PAT is well suited for a variety of pre-clinical applications, especially for studying tumor angiogenesis, cancer hypoxia, and brain disorders; it is also a promising tool for clinical applications in procedures such as cancer screening, melanoma staging, and endoscopic examination.

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