special communication A self-powered constant infusion device for use in unrestrained rats (original) (raw)
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Journal of Pharmacological and Toxicological Methods, 2000
Accurate and chronic measurements of various parameters in conscious animals are fundamental for depicting pathological chronic conditions and their etiology in many experimental models, but they are often difficult to achieve. The aim of the present work was to develop and describe step-by-step a reproducible surgical procedure and daily manipulations for continuous, chronic use of conscious rats as models towards a better understanding of various cardiovascular and renal diseases and the testing of novel pharmacological drugs. The complete apparatus involved the use of a series of specialized devices (harness, rotating swivel, revolving arm) supporting a flexible, permanently implanted vascular catheter into the left femoral artery up to the abdominal aorta connected to a miniaturized individual peristaltic pump for delivering fluid at a constant rate. Such a set-up also enabled easy, quick, and reproducible daily blood sampling for the evaluation of more than 20 parameters, including the monitoring of heart rate (HR) and blood pressure in freely moving conscious rats. The overall success and survival rate reached 98% over 14 days and could be extended further. This model represents a much needed and valuable advance in surgical research techniques to evaluate the hemodynamic, hematological, biochemical, pharmacokinetic, and toxicological profile of any new drugs over time in conscious animal models such as rats. What makes this procedure satisfactory is the long-term reliable arterial access and reproducibility of the methodological approach for accurate and continuous measurements, minimizing the stress or invasiveness associated with the use of currently employed systems. D
Continuous intravenous infusion in the unrestrained rat — procedures and results
Human & Experimental Toxicology, 1995
1 A method of continuous infusion in the unrestrained rat is described, which provides a scientifically accept able and easily maintained rodent model for use in toxicological investigations. 2 Sprague Dawley SPF rats had cannulas implanted into the vena cava via the femoral vein, and were continu ously infused with physiological saline for a total of 28 or 90 days. 3 The results indicate that there was no change in body weight, food consumption, clinical observations or clinical biochemistry of infused rats when compared to non-infused rats. There were small changes in haema tological parameters, however none were toxicological ly significant. Urinary volume was increased and uri nary specific gravity and osmolality were decreased. At macroscopic and microscopic examination there were findings of scar formation associated with the area of surgery and minimal irritation in the area of the vena cava which accommodated the cannula. 4 These results indicate that implantation of a cannu...
Use of Pressure-volume Conductance Catheters in Real-time Cardiovascular Experimentation
Heart, Lung and Circulation, 2014
Background-Most applications of pressure-volume conductance catheter measurements assess cardiovascular function at a single point in time after genetic, pharmacologic, infectious, nutritional, or toxicologic manipulation. Use of these catheters as a continuous monitor, however, is fraught with complexities and limitations. Methods-Examples of the limitations and optimal use of conductance catheters as a continuous, real-time monitor of cardiovascular function are demonstrated during inotropic drug infusion in anesthetised rats. Results-Inotropic drug infusion may alter ventricular dimensions causing relative movement of a well-positioned catheter, generating artifacts, including an abrupt pressure rise at end-systole that leads to over estimation of indices of contractility (max dP/dt) and loss of stroke volume signal. Simple rotation of the catheter, echocardiography-guided placement to the centre of the ventricle, or ventricular expansion through crystalloid infusion may correct for these artifacts. Fluid administration, however, alters left ventricular end-diastolic pressure and volume and therefore stroke volume, thereby obscuring continuous real-time haemodynamic measurements. Conclusions-Pressure-volume artifacts during inotropic infusion are caused by physical contact of the catheter with endocardium. Repeated correction of catheter position may be required to use pressure volume catheters as a continuous real-time monitor during manipulations that alter ventricular dimensions, such as inotropic therapy.
Hemodynamics of Conscious Brattleboro Rats
Annals of the New York Academy of Sciences, 1982
Institute of Physiology Czechoslovak Academy of Sciences Prague 4, CS I42 20 Czechoslovakia Vasopressin exerts distinct cardiovascular effects in many species including the rat.h However, its role in blood pressure regulation is still not c1ear.O Brattleboro rats homozygous for diabetes insipidus (DI) completely lack vasopressin,g while 50% of normal vasopressin synthesis was demonstrated in their heterozygous (HZ) littermates.' Adult female D I and HZ rats were compared in order to ascertain whether the inborn absence of vasopressin could influence their hemodynamics.
Rodent General Anesthesia Suitable for Measurement of Experimental Invasive Hemodynamics
European Journal of Biology and Biotechnology
In cases of experimentally performed invasive rodent cardiovascular measurements, selected general anesthesia for a non-recovery procedure and its proper pain control plays a fundamental role in obtaining good data recordings. Rodent anesthesia is challenging for several reasons including high metabolic rate with elevated possibility of hypothermia and hypoglycemia during the procedure, large body surface area to adjust drug medication and anticipate drug clearance. In this review article, suitable analgesia, and anesthesia to collect rodent hemodynamics is discussed with examples of commonly used methods and anesthetic combinations to assess rodent hemodynamics. In case of injectable anesthesia, hemodynamic parameters should be measured when HR and mean arterial pressure (MAP) becomes stable. If re-injection is necessary, re-evaluation of HR and MAP is crucial for data integrity. Likewise, to safeguard data quality, longitudinal collection of HRs, HR variability, MAP and body tempe...
Multiple simultaneous determinations of hemodynamics and flow distribution in conscious rat
Journal of Pharmacological Methods, 1984
A method for multiple simultaneous determinations of cardiocirculatory dynamics, regional blood flow, and total cardiac output distribution in the conscious rat preparation is described. The preparation allows for intravenous administration of agents and can be performed on animals either at rest or during treadmill exercise. Instrumentation procedures involve placement of fluid-filled catheters in the left ventricle, right atria, right jugular vein, and caudal artery. Left ventricular pressures are recorded via a modified 4F Millar transducer-tipped manometer containing a IO-cm extension of fluid-filled PE 50 placed into the left ventricle via the right carotid artery. Radionuclide-labeled microspheres (15 k 5 k) are injected into the left ventricle through the fluid-filled PE 50 at selected times for determination of cardiac output and regional blood flows using the caudal artery catheter as the source of the reference blood sample. Details and selected validation data for procedures involving anesthesia, instrumentation, recovery from anesthesia, data gathering, and data analysis are presented. Emphasis is placed on the procedures required for use of the radioactive microsphere technique in this model with special attention given to quality control of the microsphere stock, counting procedures, and computer analysis of these data.
Flow-induced errors in estimating perfusion pressure of the isolated rat kidney
Kidney International, 1982
The isolated perfused rat kidney has proven to be a very useful model for the assessment of the intrinsic renal actions of agents in a setting devoid of extrarenal influences (for review see [I]). A cell-free artificial medium of defined composition is employed usually for reasons of economy, as well as experimental design. The low viscosity of such media results in relatively high perfusate flow rates. The small size of the renal artery of the rat dictates the use of small-bore arterial cannulas that exhibit a significant resistance and induce a large decrement in pressure at the high flow rates encountered with this preparation. Since perfusion pressure is routinely monitored proximal to the arterial cannula, the pressure drop imposed by the cannula represents a potential source of error in the estimation of renal perfusion pressure. Furthermore, since perfusion pressure is an important determinant of renal function, such an erroneous estimation of this parameter may alter observed renal function inadvertently, thereby confounding the interpretation of results obtained with this model.