Cardiac substances that influence blood-pressure. I. Identification of the agent that lowers blood-pressure in anaesthetized rats.
Extracts of the atrium of the mammalian heart contain a natriuretic factor which may be associated with the atrium-specific granules. It has often been observed that the intravenous injection of a crude atrial extract into anaesthetized rats, causes a transient decrease in blood-pressure. In rabbits, this activity is present in stored aqueous extracts prepared from both atrial and ventricular tissue. The hypotensive activity, which can be readily separated from the natriuretic factor, is mainly due to the presence of adenosine and its derivatives, of which 5'-adenosine monophosphate is the major contributor. However, an extract from rabbit atrial muscle, carefully prepared under stringent conditions, caused a rapid and striking increase in blood-pressure, an activity that could not be detected in ventricular tissue.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002850:Chromatography, Gel; D004285:Dogs; D006325:Heart Atria / Q000032:analysis; D008297:Male; D009206:Myocardium / Q000032:analysis*; D011817:Rabbits; D013056:Spectrophotometry, Ultraviolet; D014020:Tissue Extracts / Q000494:pharmacology*
D014020:Tissue Extracts