The influence of synthetic oestrogen and progestogen on the rat myocardium.

Changes in wet and dry weight of the hvarl were investiniitcd in female rats iifter ovarit'ctorny antl foIlowinK the administration of oestrojifn. progestogen and a coinbinatinn of oestrogen and pnigestogcn. These clianRcs were related to hody weight iind the size of the extraceHiiIar fluid .space of the myocardium. Heart dry weiglit and iKidy weight in the animals given eombined oestrogen and progestogen were maintained closer to tho-se of the it)ntnil.s than in the animals given eitlicr hormone separately. Ovariectomy rrsultetl in an iiicrea.sc in I>ody weight and a relative decrease in wet and dr>' weight of the heart. The extracellular fluid space was increa.sed in the hearts of animals treated with a ctimbination of oestrogen and progestogt-n, whereas it was not altered in ovariectomized animals or in those given either hormone separately.