Phenylephrine, endothelin, prostaglandin F2alpha' and leukemia inhibitory factor induce different cardiac hypertrophy phenotypes in vitro.

ABSTRACT

In these studies, we show that endothelin (ET), leukemia inhibitory factor (LIF), phenylephrine (PE), and prostaglandin F2alpha (PGF2alpha), which are all hypertrophic for neonatal rat cardiac myocytes in culture, induce distinct morphological, physiological, and genetic changes after a 48-h treatment. Transmission electron microscopy revealed differences in myofibril organization, with ET-treated cells containing the most mature-looking myofibrils and PGF2alpha- and LIF-treated cells the least. ET- and PE-treated cultures contained the same number of beating cells as control, but LIF and PGF2alpha treatment increased the number of beating cells 180%. Treatment with LIF, PE, and PGF2alpha increased the beat rate to 3.3 times that of control. After exposure to the beta-adrenergic agonist isoproterenol, the beat rate increased 50% for PGF2alpha' 54% for PE, 84% for LIF, and 125% for control. ET treatment did not increase the beat rate, nor did these cells respond to isoproterenol. ET, LIF, and PE increased the production of atrial natriuretic peptide (ANP) by three-fold and PGF2alpha by 18-fold over nontreated cells. Brain natriuretic peptide (BNP) was increased fourfold by ET and PE, 16-fold by LIF, and 29-fold by PGF2alpha. Interestingly, on a pmol/L basis, only LIF induced more BNP than ANP. Treatment with all agents led to a similar pattern of gene induction increased expression of the embryonic genes for ANP and skeletal alpha-actin, and less than a twofold change in the constitutively expressed gene myosin light chain-2, with the exception that LIF did not induce skeletal alpha-actin. Each agent, however, induced ANP mRNA with a different time-course. We conclude that at least four distinct cardiac myocyte hypertrophy response programs can be induced in vitro. Further studies are necessary to determine whether these correlate to the different types of cardiac hypertrophy seen in vivo.