ABSTRACT
Experiments were performed to investigate the effects of long-term treatment with adrenergic receptor antagonist on electrical remodeling of the left ventricle with chronic pressure-overload. New Zealand rabbits underwent subtotal banding of superrenal abdominal aorta. At 10 weeks after surgery, echocardiography examination was performed, then action potential (AP), inward rectifier potassium current (I(Ki)), delayed rectifier potassium current (I(K)) and Na(+)/Ca(2+) exchanger current (I(Na(+)/Ca(2+))) were recorded in midmyocardial cells isolated from left ventricle of abdominal aorta banded group (banded group), abdominal aorta banding plus Carvedilol intervention group (Carvedilol group), and normal control group rabbits by using the whole-cell patch-clamp techniques. The results showed that left ventricular mass index in control, banded, and Carvedilol groups were 1.78+/-0.06 (n=7), 2.33+/-0.11 (n=7), and 1.87+/-0.08 (n=7), respectively (banded vs control and Carvedilol, P<0.01). At basic cycle length of 2 s, AP duration (measured at 90% repolarization, APD(90), ms) in control, banded, and Carvedilol groups were 522.0+/-19.5 (n=6), 664.7+/-46.2 (n=7), 567.8+/-14.3 (n=8) respectively (banded vs control, P<0.01; Carvedilol vs banded, P<0.05). At test potential of -100 mV, inward I(Ki) density (pA/pF) in control, banded, and Carvedilol groups were -11.8+/-0.50 (n=8), -8.07+/-0.28 (n=8), -10.69+/-0.35 (n=8) respectively (banded vs control and Carvedilol, P<0.01). At test potential of +50 mV, I(K) tail current density (pA/pF) in control, banded, and Carvedilol groups were 0.59+/-0.04 (n=8), 0.40+/-0.02 (n=9), 0.51+/-0.02 (n=8) respectively (banded vs control, P<0.01; Carvedilol vs banded, P<0.05). At test potential of +60 mV, outward I(Na(+)/Ca(2+)) density (pA/pF) in control, banded, and Carvedilol groups were 1.06+/-0.11 (n=8), 1.54+/-0.10 (n=9), 1.24+/-0.07 (n=8), respectively (banded vs control and Carvedilol, P<0.01). At test potential of -120 mV, inward I(Na(+)/Ca(2+)) density (pA/pF) in control, banded, and Carvedilol groups were -0.54+/-0.06 (n =8), -0.75+/-0.04 (n=9), -0.60+/-0.03 (n=8), respectively (banded vs control, P<0.01; Carvedilol vs banded, P<0.05). It is shown that long-term treatment with Carvedilol not only prevents development of cardiac hypertrophy, but also improves the electrophysiological alterations in rabbit hearts with chronic pressure-overload. This finding may add new electrophysiological evidence for the treatment of heart failure and hypertension with adrenergic receptor antagonist.
Subject(s)
Animals , Female , Male , Rabbits , Action Potentials , Adrenergic Antagonists , Pharmacology , Carbazoles , Pharmacology , Cardiac Output, Low , Electrophysiology , Patch-Clamp Techniques , Propanolamines , Pharmacology , Ventricular RemodelingABSTRACT
<p><b>OBJECTIVE</b>To study the lipid regulatory effect of Xuezhikang (XZK) and its effects on serum oxidized low density lipoprotein (OX-LDL), C-reactive protein (CRP) and fibrinogen (FIB) in patients with unstable angina pectoris (UAP).</p><p><b>METHODS</b>UAP patients with hyperlipidemia were treated with XZK 0.6 g, orally taken, twice a day for 2 successive months followed by half dosage for 2 months. To UAP patients with normal blood lipids, Vit E was given orally for 4 months. Levels of blood lipids, OX-LDL, CRP, FIB at the time of entry, 1st and 2nd month of the therapeutic course were observed and end-point events in the two groups was compared.</p><p><b>RESULTS</b>XZK can reduce the serum level of total cholesterol, low density lipoprotein after being administered for 1 month, and the effect further elevated after 2 months. Its effect in lowering triglycerides and increasing high density lipoprotein initiated after 2 months administration. Compared with effect of Vit E, XZK can significantly lower the serum OX-LDL, CRP and FIB after 2 months administration, and reduce the end-point events in 4 months.</p><p><b>CONCLUSION</b>XZK has good regulatory effect on blood lipids, it also can inhibit the development of inflammation in coronary plaque, therefore, is beneficial to the prognosis of UAP patients.</p>