Myocardial Hypertrophy Produced by Chronic Infusion of Subhypertensive Doses of Norepinephrine in the Dog

Six dogs were continuously infused with subhypertensive doses of norepinephrine (NE) for periods of 6 to 63 weeks and in these dogs, mean left ventricular weight was increased above normal.

Abstract

Six dogs were continuously infused with subhypertensive doses of norepinephrine (NE) for periods of 6 to 63 weeks. In these dogs, mean left ventricular weight, 67.3 ± 2.5 gm/M2 (mean ± SEM), was increased above normal, 59.2 ±1.4 gm/M2 (p < 0.005); in contrast, neither right ventricular nor septal weights were increased above normal. In addition, in two dogs chronically infused with the NE diluent, neither ventricular nor septal weights were greater than normal. In the dogs with chronic infusion of NE, mean wall thicknesses at the LV base and apex were greater than normal (p < 0.005). These results demonstrate that chronic infusion of subhypertensive doses of NE cause LV hypertrophy in the dog. We postulate that in the pressure-overloaded heart, stress to the ventricular wall stimulates the release of NE into the myocardium, which then initiates the hypertrophy process. Six dogs were continuously infused with subhypertensive doses of norepinephrine (NE) for periods of 6 to 63 weeks. In these dogs, mean left ventricular weight, 67.3 ± 2.5 gm/M2 (mean ± SEM), was increased above normal, 59.2 ±1.4 gm/M2 (p < 0.005); in contrast, neither right ventricular nor septal weights were increased above normal. In addition, in two dogs chronically infused with the NE diluent, neither ventricular nor septal weights were greater than normal. In the dogs with chronic infusion of NE, mean wall thicknesses at the LV base and apex were greater than normal (p < 0.005). These results demonstrate that chronic infusion of subhypertensive doses of NE cause LV hypertrophy in the dog. We postulate that in the pressure-overloaded heart, stress to the ventricular wall stimulates the release of NE into the myocardium, which then initiates the hypertrophy process.