angiotensinogen and Hemorrhage

Angiotensin II, the biologically active component of the renin-angiotensin system, acts throughout the body to produce an impressive number of cardiovascular, endocrine, metabolic, and behavioral effects. Major actions include elevation of arterial pressure, stimulation of aldosterone secretion, and a variety of effects on the kidneys, brain, and pituitary. Investigation of the role of the renin-angiotensin system in physiological regulation has been greatly facilitated by the availability of specific inhibitors of the formation or actions of angiotensin II, most notably converting-enzyme inhibitors and angiotensin receptor antagonists. Studies with these agents have clearly shown that the renin-angiotensin system plays an important role in the defense of body balance and blood pressure in hypovolemic state, including sodium deficiency and hemorrhage. The inhibitors also lower blood pressure in some forms of hypertension, and converting-enzyme inhibitors are proving to be effective antihypertensive agents.

Topics: Aldosterone; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Blood Pressure; Brain; Hemorrhage; Humans; Hypertension; Kidney; Peptidyl-Dipeptidase A; Pituitary Gland; Renin; Renin-Angiotensin System; Water-Electrolyte Balance

Topics: Anesthetics; Angiotensinogen; Angiotensins; Animals; Arterioles; Blood Pressure; Dogs; Hemodynamics; Hemorrhage; Humans; Hypotension; Kidney; Oxygen Consumption; Radioisotopes; Renal Artery; Renal Circulation; Sympathetic Nervous System; Vasoconstriction; Vasodilation

The purpose of this study was to analyze functional polymorphisms in candidate genes (methylenetetrahydrofolate reductase [MTHFR]677C>T, MTHFR1298A>C, factor 5 1691G>A [FVL], and angiotensinogen (AGT)-6G>A) in relation to a hypothesized placental hemorrhage pathway to preterm delivery (PTD).. We assessed maternal genotypes, pregnancy outcomes, and placental pathologic evidence among 560 white and 399 black women who were recruited at mid trimester into a prospective cohort study (1998-2004). Odds of dominant genotypes were calculated for PTDs with (n = 56) or without (n = 177) evidence of placental hemorrhage (referent = term) with the use of race-stratified polytomous logistic regression models.. Among white women, FVL GA/AA and AGT(-6) GA/AA were both associated with hemorrhage-related PTDs (odds ratio [OR], 4.8; 95% confidence interval [CI], 1.6-14.2 and OR, 3.8; 95% CI, 1.3-10.5, respectively), but not other PTDs (ORs, 1.2 and 0.9, respectively). FVL GA/AA was associated with placental abruption (OR, 5.8; 95% CI, 1.1-30) among white women. All results were null for MTHFR genotypes.. FVL and AGT variant genotypes were associated specifically with hemorrhage-related PTDs.

Topics: Adult; Angiotensinogen; Factor V; Female; Gene Frequency; Genotype; Hemorrhage; Humans; Logistic Models; Methylenetetrahydrofolate Reductase (NADPH2); Placenta Diseases; Point Mutation; Polymorphism, Genetic; Pregnancy; Pregnancy Outcome; Premature Birth; Renin-Angiotensin System; Thrombophilia; Young Adult

Renal renin and the juxtaglomerular cells evolved in primitive bony fishes, whereas the macula densa emerged later in vertebrate phylogeny. We attempted to determine whether a renal arteriolar baroreceptor exists in the toadfish Opsanus tau, which possess renin and granulated cells in the kidneys, but lack glomeruli and macula densa. Cumulative hemorrhage of 1.5, 3, 6, 12, and 18 ml/kg, or a single massive bleeding from unanesthetized toadfish, kept in 50% seawater, caused an immediate and significant decrease in mean aortic pressure and stepwise increases (5-20 times) of plasma renin activity (PRA). Papaverine (10 mg/kg) caused hypotension and increased PRA. Minoxidil (6-12 mg/kg) neither decreased blood pressure nor increased PRA. The results suggest that toadfish respond to hemorrhage and acute hypotension with renin release despite the absence of a macula densa. It remains to be determined whether decreased renal perfusion pressure due to decreased dorsal aortic pressure stimulated the receptor in the granulated cells or whether the renal nerves may be involved.

Topics: Angiotensinogen; Animals; Female; Fishes; Hematocrit; Hemorrhage; Hypotension; Male; Minoxidil; Papaverine; Pressoreceptors; Renal Artery; Renin

Topics: Angiotensinogen; Angiotensins; Hemorrhage; Hypotension