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Chronic administration of nicardipine attenuates myocardial stunning in isolated rabbit hearts
A E Moreyra1, R J Gelpi, S M Mosca
1UMDNJ-Robert Wood Johnson Medical School Department of Medicine, New Brunswick.
Abstract:
The purpose of this study was to evaluate the effects of the chronic administration of a calcium channel blocker, nicardipine, on systolic and diastolic alterations occurring during myocardial stunning in isolated rabbit hearts. Rabbits were pretreated with nicardipine 20 mg (O.I.D.) for 30 days. Then hearts were isolated (group II) and compared with control hearts (group I) in their response to 20 min of global ischemia and 30 min of reperfusion. Coronary flow and heart rate were kept constant. Left ventricular isovolumic developed pressure (LVDP), its first derivative (dP/dt), and end diastolic pressure (LVEDP) were measured. After isolation, no statistically significant changes were detected in LVDP, +dP/dtmax, LVEDP, or coronary resistance in hearts of rabbits with or without the pharmacological intervention. Early after the onset of reperfusion, LVDP and +dP/dtmax partially recovered in a similar way in groups I and II. Late in reperfusion LVDP stabilized at 48 +/- 7% in group I and 71 +/- 6% in group II (P < 0.05) and +dP/dtmax stabilized at 56 +/- 7% and 79 +/- 6% (P < 0.05), respectively. Diastolic dysfunction was manifested by a 217 +/- 39% increase in LVEDP (P < 0.05) in group I, and 140 +/- 31% in group II (P < 0.05). The isovolumic relaxation time constant (tau, tau) increased from 70 +/- 5 to 151 +/- 27 ms (P < 0.05), and from 66 +/- 6 to 97 +/- 10 ms. (NS) in groups I and II, respectively at 5 min of reperfusion. This relaxation parameter returned to normal values in the late reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Chronic nicardipine treatment improved systolic function and reduced diastolic dysfunction in isolated rabbit hearts after ischemia-reperfusion injury. This calcium channel blocker demonstrated protective effects against myocardial stunning.
Area of Science:
- Cardiovascular Physiology
- Pharmacology
Background:
- Myocardial stunning is a post-ischemic dysfunction.
- Calcium channel blockers are used to treat cardiovascular conditions.
Purpose of the Study:
- To investigate the protective effects of chronic nicardipine administration on myocardial stunning in isolated rabbit hearts.
Main Methods:
- Rabbits were pretreated with nicardipine (20 mg O.I.D.) for 30 days.
- Isolated hearts underwent global ischemia (20 min) and reperfusion (30 min).
- Left ventricular developed pressure (LVDP), dP/dt, and end-diastolic pressure (LVEDP) were measured.
Main Results:
- Nicardipine treatment significantly improved LVDP and +dP/dtmax recovery during late reperfusion.
- Diastolic dysfunction, indicated by increased LVEDP and prolonged relaxation time constant (tau), was attenuated by nicardipine.
- No significant changes in baseline cardiac function or coronary resistance were observed.
Conclusions:
- Chronic nicardipine administration offers significant protection against systolic and diastolic dysfunction during myocardial stunning.
- Nicardipine's beneficial effects on post-ischemic cardiac function warrant further investigation.