Development of isoproterenol-induced cardiac hypertrophy.
The development of cardiac hypertrophy was studied in adult female Wistar rats following daily subcutaneous injections of isoproterenol (ISO) (0.3 mg/kg body weight). A time course was established for the change in tissue mass, RNA and DNA content, as well as hydroxyproline content. Heart weight increased 44% after 8 days of treatment with a half time of 3.4 days. Ventricular RNA content was elevated 26% after 24 h of a single injection and reached a maximal level following 8 days of therapy. The half time for RNA accumulation was 2.0 days. The total content of hydroxyproline remained stable during the first 2 days of treatment but increased 46% after 4 days of therapy. Ventricular DNA content was unchanged during the early stage (1-4 days) of hypertrophic growth but increased to a new steady-state level 19% above the controls after 8 days of treatment. Intraventricular pressures and coronary flow measures were similar for control and experimental animals following 4 days of developed hypertrophy. However, dP/dt in the ISO-treated hearts was slightly but significantly (P less than 0.05) elevated. These data indicate that the adaptive response to ISO shows an early hypertrophic phase (1-4 days) characterized by a substantial increase in RNA content and cardiac mass in the absence of changes in DNA. However, prolonged stimulation (8-12 days) appears to represent a complex integration of both cellular hypertrophy and hyperplasia within the heart.
D000818:Animals; D001834:Body Water / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D006332:Cardiomegaly / Q000139:chemically induced* / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D005260:Female; D006207:Half-Life; D006439:Hemodynamics / Q000187:drug effects; D006909:Hydroxyproline / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology*; D009124:Muscle Proteins / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D009929:Organ Size / Q000187:drug effects; D012313:RNA / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D009124:Muscle Proteins; D012313:RNA; D004247:DNA; D007545:Isoproterenol; D006909:Hydroxyproline