Cardiac substances that influence blood-pressure. II. Potent pressor activity in rat and rabbit atrial muscle.
In addition to their natriuretic, diuretic and vasodilator activities, freshly prepared aqueous extracts of either rat or rabbit atrial myocardium were shown to elicit significant increases in the blood-pressure of anaesthetized rats. Small aliquots (0.05 ml) intravenously administered caused a transient rise in mean arterial blood-pressure of up to 20%. Slow infusion of 0.4 ml right atrial extract (corresponding to about one half of a rabbit right atrial lobe) during 90 seconds caused the expected natriuresis and diuresis, together with a sustained elevation in arterial blood-pressure (ca 25%) that returned to normal within 3 minutes. This potent pressor activity could not be detected in ventricular extracts. It was furthermore readily separable from the natriuretic peptides and catecholamines by ultrafiltration. The atrial pressor factor is a small proteolytically unstable molecule (300-1000 dalton).
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D006325:Heart Atria / Q000032:analysis; D008297:Male; D008970:Molecular Weight; D009206:Myocardium / Q000032:analysis*; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D014020:Tissue Extracts / Q000494:pharmacology
D014020:Tissue Extracts