Splanchnic and systemic hemodynamics in mice using a radioactive microsphere technique.

Area of Science:

• Physiology
• Cardiovascular Research
• Animal Models

Background:

• Mice are vital for studying human diseases.
• Accurate measurement of systemic and hepatic blood flow in mice is crucial but lacks established techniques.
• Conventional left ventricular microsphere injection in mice has a high failure rate (68%) due to complications.

Purpose of the Study:

• To evaluate the efficacy of carotid artery injection for measuring systemic and regional hemodynamics in mice.
• To establish reliable methods for assessing blood flow in mouse models.
• To overcome limitations of previous microsphere injection techniques in mice.

Main Methods:

• Modified radioactive microsphere technique with injection into the carotid artery near the aortic arch.
• Assessment of microsphere distribution, mixing, and impact on blood pressure.
• Measurement of portal venous inflow, renal blood flow, cardiac output, and cardiac index.

Main Results:

• Carotid artery injection achieved adequate microsphere mixing in 78% and sufficient tissue counts in 91% of mice.
• Portal venous inflow was 1.8 ± 0.3 ml/min/g liver tissue; renal blood flow was 5.1 ± 0.75 ml/min/g tissue.
• Cardiac output averaged 12.1 ± 1.2 ml/min, with a cardiac index of 462 ± 47 ml/min/kg body weight.

Conclusions:

• Carotid artery injection is a viable alternative for radioactive microsphere studies in mice.
• The technique, with modifications, allows for accurate hemodynamic assessment in mouse models.
• This adaptation enhances the utility of mice in cardiovascular and disease research.