Chronic MK421 fails to modify evolution of hypertension in neonatally coarcted pups

Angiotensin-converting enzyme inhibitor therapy for ventricular dysfunction in infants, children and adolescents: a review

Angiotensin-converting enzyme (ACE) inhibitors have become an important part of the pharmacologic armamentarium in the battle against treatment of ventricular dysfunction. There have been a number of large controlled, randomized trials in adults with both asymptomatic and symptomatic ventricular dysfunction, which confirm the safety and efficacy of this category of drugs for the treatment of this potentially lethal condition. ACE inhibitors may be used to treat infants, children and adolescents with asymptomatic and symptomatic ventricular dysfunction as well. The data supporting their use in children is less complete than that concerning the treatment of adults. We review here the various causes of ventricular dysfunction and congestive heart failure (CHF) in infants, children, and adolescents; the data available regarding treatment of these conditions with ACE inhibitors, and the safety and efficacy of these drugs for the various conditions. The pharmacokinetics and proposed mechanisms of action of ACE inhibitors in children are reviewed, as are speculated long-term results of ACE inhibitor use in cohorts of growing children. Recommendations are made for future studies.

Vasopressor mechanisms in acute aortic coarctation hypertension

Angiotensin II (ANG II) and vasopressin (AVP) act together with the mechanical effect of aortic constriction in the onset of acute aortic coarctation hypertension. Blockade of ANG II and AVP V1 receptors demonstrated that ANG II acts on the prompt (5 min) rise in pressure whereas AVP is responsible for the maintenance (30-45 min) of the arterial pressure elevation during aortic coarctation. Hormone assays carried out on blood collected from conscious rats submitted to aortic constriction supported a role for ANG II in the early stage and a combined role for both ANG II and AVP in the maintenance of proximal hypertension. As expected, a role for catecholamines was ruled out in this model of hypertension, presumably due to the inhibitory effect of the sinoaortic baroreceptors. The lack of afferent feedback from the kidneys for AVP release from the central nervous system in rats with previous renal denervation allowed ANG II to play the major role in the onset of the hypertensive response. Median eminence-lesioned rats exhibited a prompt increase in proximal pressure followed by a progressive decline to lower hypertensive levels, revealing a significant role for the integrity of the neuroaxis in the maintenance of the aortic coarctation hypertension through the release of AVP. In conclusion, the important issue raised by this model of hypertension is the likelihood of a link between some vascular territory-probably renal-below the coarctation triggering the release of AVP, with this vasoconstrictor hormone participating with Ang II and the mechanical effect of aortic constriction in the acute aortic coarctation hypertension.

Renal hypertension following aortic constriction is abolished by angiotensin II converting enzyme inhibitor, but not by low-salt diet

This study evaluates the role of different sodium intakes and the role of angiotensin II in the development and the maintenance of renovascular hypertension in rats with constriction of the aorta proximal to the renal arteries. The rats were studied 3 weeks after surgery when the hypertension was well established. Glomerular filtration rate was decreased and filtration fraction was increased in rats with proximal aortic constriction. Low and high salt intakes had no effect on glomerular filtration and filtration fraction. Treatment with angiotensin II converting enzyme inhibitor increased the glomerular filtration rate and reduced the filtration fraction in rats with proximal aortic constriction to the same levels as in control rats. Serum levels of angiotensin II were about the same in rats with proximal aortic constriction as in control rats. Conclusion. The renovascular hypertension in proximal aortic constriction is influenced by locally formed angiotension II but not by alterations in salt intake.