title: Left ventricular pressure-volume relationship in conscious mice.
abstract: With the availability of transgenic models, the mouse has become an increasingly important subject for genetic-hemodynamic studies. Recently, we developed a technique to measure left ventricular (LV) pressure in conscious mice with an implanted LV polyethylene tube. We extended our new method by evaluating the LV pressure-volume relationship and examined the feasibility of this method in this study. We studied 17 male mice (age, 11-20 wk) with a conductance catheter inserted into the LV through the polyethylene tube. Load-independent parameters of contractility derived from pressure-volume relationship [slope of the end-systolic pressure-volume relationship (E(es)), slope of the maximum first derivative of LV pressure (dP/dt(max))-end-diastolic volume (EDV) relation, and preload-recruitable stroke work (PRSW)] were evaluated by inferior vena caval occlusion with an implanted snare. LV function assessed by this technique on two different days showed that the parameters were very similar, indicating reproducibility. Both linear and nonlinear regression analyses were performed for E(es). Contractility was enhanced by isoproterenol (E(es), 13.1 +/- 6.6 to 20.8 +/- 8.7 mmHg/microl; dP/dt(max)-EDV, 496 +/- 139 to 825 +/- 178 mmHg.s(-1).microl(-1); and PRSW, 110 +/- 23 to 127 +/- 21 mmHg), depressed by atenolol (E(es), 14.5 +/- 6.1 to 4.6 +/- 2.0 mmHg/microl; dP/dt(max)-EDV, 543 +/- 188 to 185 +/- 94 mmHg.s(-1).microl(-1); and PRSW, 117 +/- 20 to 70 +/- 15 mmHg) and isoflurane (E(es), 12.3 +/- 6.0 to 5.7 +/- 2.1 mmHg/microl; dP/dt(max)-EDV, 528 +/- 172 to 164 +/- 68 mmHg/s.microl; and PRSW, 124 +/- 19 to 48 +/- 10 mmHg), significantly. In conclusion, this is the first description of the LV pressure-volume relationship in conscious mice. These findings suggest that this method is feasible to detect changes of contractility in the conscious state, allowing serial assessment of pressure-volume-derived cardiac function indexes over time without anesthesia or repeated surgery.
authors.affiliation: Cardiology Division, Dept. of Medicine, Univ. of California, San Francisco, 505 Parnassus Ave., Box 0124, San Francisco, CA 94143-0124, USA.
authors.forename: Shuji
authors.initials: S
authors.lastname: Joho
authors.forename: Shinji
authors.initials: S
authors.lastname: Ishizaka
authors.forename: Richard
authors.initials: R
authors.lastname: Sievers
authors.forename: Elyse
authors.initials: E
authors.lastname: Foster
authors.forename: Paul C
authors.initials: PC
authors.lastname: Simpson
authors.forename: William
authors.initials: W
authors.lastname: Grossman
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D001795:Blood Pressure Determination / Q000295:instrumentation* / Q000379:methods*; D002306:Cardiac Volume / Q000502:physiology*; D003243:Consciousness / Q000502:physiology; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013318:Stroke Volume / Q000502:physiology*; D016276:Ventricular Function; D016277:Ventricular Function, Left / Q000502:physiology*