Effects of growth hormone supplementation on left ventricular morphology and myocyte function with the development of congestive heart failure

Background-Release of growth hormone (GH), putatively through alterations i n insulin growth factor-1 (IGF-1) levels, has been implicated to influence left ventricular (LV) myocardial structure and function. The objective of t his study was to determine contributory mechanisms by which GH supplementat ion may influence LV function with the development of congestive heart fail ure (CHF). Methods and Results-Pigs were assigned to the following groups: (1) chronic pacing at 240 bpm for 3 weeks (n = 10), (2) chronic pacing and GH suppleme ntation (200 mu g.kg(-1).d(-1), n = 10), and (3) controls (n = 8). GH treat ment increased ICF-1 plasma levels by nearly 2.5-fold throughout the pacing protocol. In the untreated pacing CHF group, LV fractional shortening was reduced and peak wall stress increased. In the pacing CHF and GH groups, LV fractional shortening was higher and LV wall stress lower than untreated C HF values. Steady-state myocyte velocity of shortening was reduced with pac ing CHF and was unchanged from CHF values with GH treatment. In the presenc e of 25 nmol/L isoproterenol, the change in myocyte shortening velocity was reduced in the untreated CHF group and increased in the GH-treated group. LV sarcoplasmic reticulum Ca2+-ATPase abundance was reduced with pacing CHF but was normalized with GH treatment. Conclusions-Short-term GH supplementation improved LV pump function in paci ng CHF as a result of favorable effects on LV remodeling and contractile pr ocesses. Thus, GH supplementation may serve as a novel therapeutic modality in developing CHF.