Microsphere and dilution techniques for the determination of blood flows and volumes in conscious mice

Abstract

Although the mouse is the most commonly used transgenic species, little is known regarding cardiovascular and fluid homeostasis in this animal. Therefore, the reference microsphere and dilution techniques were adapted for the measurement of cardiac output (CO), regional blood flows, and intravascular fluid volumes in the conscious mouse. Previously acclimatized C3H mice were studied 4-5 h after surgery and recovery from anesthesia. Approximately 40,000 85Sr-labeled microspheres were injected into the left ventricle while a reference sample was withdrawn at one of two rates from the femoral artery. 51Cr and 125I were used for the determination of blood volume (BV), plasma volume (PV), and Fcells ratio (whole body hematocrit/large vessel hematocrit). CO and BV in the conscious mouse were 16 +/- 1.4 ml/min and 2.3 +/- 0.1 ml, respectively. Anesthesia lowered heart rate, blood pressure, PV, and altered the distribution of CO. Two successive injections of 15,000-20,000 microspheres were tolerated in the mouse without an increase in total peripheral resistance. The results indicate that the microsphere and indicator dilution techniques can be applied to study cardiovascular and fluid homeostasis in the mouse.

S-nitrosylation therapy to improve oxygen delivery of banked blood

“…Renitrosylation of blood in these initial experiments used an established NO methodology (Materials and Methods) that increases SNO-Hb concentrations without increasing nitrite (32,35,39). Normovolemic mice received the human equivalent of one unit (200 μL) of RBCs [∼10% of estimated blood volume (40)] that had been stored for 1 or 7 d. Representative and group oxygenation responses of the mouse thigh muscle bed are presented in Fig. 1.…”

In vivo assessment of absolute perfusion and intracapillary blood volume in the murine myocardium by spin labeling magnetic resonance imaging

“…In our data, typical relative errors of the fit parameters A, B, and T* 1 (see Eq. [4]) are in the range of up to 3% per pixel. As a consequence, relative errors in the murine myocardial perfusion are in the range of up to 40% per pixel.…”

“…One possible approach is the quantification of the coronary flow in the isolated mouse heart by ultrasonic flow probes (3). The injection of labeled microspheres has also been applied to quantify the perfusion in murine myocardium (4,5). However, an important drawback of these ex vivo techniques is their invasiveness, which inhibits serial measurements in the same animal.…”

Study of the Murine Cardiac Mechanical Function Using Magnetic Resonance Imaging: The Current Status, Challenges, and Future Perspectives

“…Based on the extensive number of literature publications that focused on the elucidation of the basic principles of cardiovascular physiology (during the early and latter half of the 20 th century), including the autoregulation of blood flow in rats and canine [Feng 2001, Sandgaard 2002], important differences exist in mouse and man with regard to perfusion, capillary density [Stoker 1982, Rakusan 1994, total blood volume (2.5 ml in the mouse compared to 400-500 ml in humans), relative distribution of blood flow in the capillary bed and redistribution capability subject to stimuli (temperature, anesthesia) [Barbee 1992, Rosenblum 1997, Sarin 1990, angiogenetic capacity and formation of collateral vessels, as well as the resting coronary reserve, as factors that primarily project to ischemia-reperfusion studies (or other cardiovascular pathology models) and comparative analyses between pigs, canine, and man.…”

“…However differences do exist, including the increased sensitivity of blood pressure to anesthesia and temperature, especially under conditions of stress [Barbee 1992 …”