The purpose of this to investigate the effects of adrenomedullin(ADM) on cardiac hypertrophy andthe loss of myocardial sarcolemmal vesicles (MSLV) Na-Ca exchanger in LNNA(via chronic nitric oxideblockade)-induced hypertensive and cardiac hypertrophic rats. The results show that :the mean arterialpressure (MAP) and left ventricular index(LVI) of LNNA group have increased by 57.4%and 18.0% respectivelyover that of the control(P<0.01)

but its MSLV calcium uptake is lower than the control(p<0.01 or 0.01); 2 theMAP and the LVI of ADM group have decreased to 80.4% and 88.7% of the LNNA(P<0.01)

its calcium uptakerate of MSLV is higer than the LNNA (P<0.05); 2

the difference of Km of MSLV Na-Ca exchanger amongcontrol

LNNA and and ADM groups is not obvious (7

51

7

04 and 7

57uM respectively)

while the difference of theirVmax is great :6.38

4

32 and 5

45nmol/mg pr/min respectively. These results suggest that ADM has antagonism tocardiac hypertropy and that ADM can alleviate the loss of MSLV Na-CA exchanger induced by LNNA and toeffect of ADM may be one of the mechanisms of ADM to antagonize cardiac gypertreophy.