Related Experiment Videos
Microvascular changes in the heart during chronic arterial hypertension
1Center for Microvascular, Lymphatic Studies and University of Texas Medical School, Houston 77030.
Insights
Chronic renovascular hypertension in dogs increased myocardial lymph flow, suggesting altered microvascular permeability or exchange surface area. Further studies are needed to pinpoint the exact cause in hypertensive hearts.
Area of Science:
- Cardiovascular Physiology
- Renal Hypertension
- Microvascular Dynamics
Background:
- Chronic renovascular hypertension is a significant cardiovascular condition.
- Understanding changes in myocardial microvascular permeability is crucial for managing hypertensive heart disease.
Purpose of the Study:
- To investigate alterations in myocardial microvascular permeability in a canine model of chronic renovascular hypertension.
- To assess the impact of hypertension on myocardial lymph flow and protein leakage.
Main Methods:
- Induction of hypertension using the one-kidney, one-clip Goldblatt model in dogs.
- Measurement of systemic and coronary pressures, myocardial lymph flow, interstitial fluid pressure, and lymph-to-plasma protein concentration ratio (CL/CP).
- Determination of the filtration-independent reflection coefficient (sigma) to assess microvascular permeability.
Main Results:
- Hypertensive dogs exhibited significantly higher myocardial lymph flow rates compared to control animals.
- No significant difference in CL/CP was observed between hypertensive and control groups.
- Elevated coronary sinus pressure was used to evaluate microvascular permeability independent of surface area.
Conclusions:
- Chronic renovascular hypertension leads to increased myocardial lymph flow.
- The observed increase in lymph flow may indicate altered myocardial microvascular permeability or an increased exchange surface area.
- Further research is warranted to elucidate the precise mechanisms of microvascular changes in hypertension.
Abstract:
Changes of myocardial microvascular permeability in chronic renovascular arterial hypertension were studied. Hypertension was induced in dogs utilizing a one-kidney, one-clip Goldblatt model. Systemic arterial pressure, coronary sinus pressure, systemic venous pressure, myocardial lymph flow rate, myocardial interstitial fluid pressure, and the lymph-to-plasma protein concentration ratio for total plasma proteins and for beta-lipoprotein (CL/CP) were determined in control animals and 4-6 weeks following the Goldblatt procedure in hypertensive animals. Control values for the normotensive animals were 123 +/- 17 mm Hg, 7.3 +/- 1.3 mm Hg, 2.5 +/- 2.1 mm Hg, 3.1 +/- 2.1 ml/hr, 14.9 +/- 3.1 mm Hg, 0.82, and 0.33, respectively, while control values for the chronically hypertensive dogs were 160 +/- 20 mm Hg, 7.8 +/- 1.9 mm Hg, 2.9 +/- 2.5 mm Hg, 10.5 +/- 2.5 ml/hr, 24.8 +/- 3.7 mm Hg, 0.87, and 0.31, respectively. Under control conditions, myocardial lymph flow rate was significantly higher in the hypertensive group while no difference could be demonstrated in CL/CP between the two groups. This is indicative of either a change in myocardial microvascular permeability or an increase in microvascular exchange surface area. Coronary sinus pressure was elevated in both groups in order to increase transmicrovascular fluid flux and determine the filtration-independent reflection coefficient (sigma) for each group. Sigma is a surface area-independent indicator of microvascular permeability when determined for specific protein molecules at high transmicrovascular fluid fluxes.(ABSTRACT TRUNCATED AT 250 WORDS)