Slow rise and diurnal change of blood pressure with saralasin and angiotensin II in rats.
Our objectives were to determine whether saralasin, like angiotensin II, raises blood pressure gradually when given by constant infusion and whether either agent alters the diurnal variation of arterial pressure. Eight female Wistar rats were infused intravenously with 5% dextrose for 2 days, then with saralasin at 10 micrograms . kg-1 . min-1 for 4 days, and finally with dextrose for 2 days. Six other rats were infused with angiotensin II (20 ng . kg-1 . min-1) instead of saralasin. Mean arterial pressure (MAP) was recorded continuously. Saralasin and angiotensin II gradually raised MAP in all rats, by 22.0 mmHg on the 4th day of saralasin and by 41.7 mmHg on the 4th day of angiotensin II. Both agents also increased the diurnal variation of blood pressure, MAP increasing 8.3-20.6 mmHg during the night and falling 6.7-19.1 mmHg during the day. Variability of arterial pressure was also increased by saralasin and in an earlier experiment by angiotensin II. We conclude that saralasin has a slow pressor action similar to that of angiotensin II but distinct in its timing both from the rapid agonist action of saralasin and from the acute vasoconstrictor action of angiotensin II. These effects of saralasin may compromise interpretation of experiments in which the drug is given by prolonged infusion to assess the role of angiotensin II.
D000804:Angiotensin II / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002940:Circadian Rhythm / Q000187:drug effects*; D004231:Diuresis / Q000187:drug effects; D005260:Female; D051381:Rats; D011919:Rats, Inbred Strains; D012504:Saralasin / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism
D000804:Angiotensin II; D012964:Sodium; D012504:Saralasin