Key result
Within 6 weeks, the AT1 receptor antagonist downregulated synthetic-type myosin heavy chains more potently than the ACE inhibitor in spontaneously hypertensive rat aortic tunica media.
Why the study?
Does an AT1 receptor antagonist downregulate synthetic-type myosin heavy chains more efficiently than an ACE inhibitor in spontaneously hypertensive rats?
Does an AT1 receptor antagonist downregulate synthetic-type myosin heavy chains more efficiently than an ACE inhibitor in spontaneously hypertensive rats?
In spontaneously hypertensive rats, AT1 receptor antagonists may modulate the cellular composition of myosin heavy chain isoforms in aortic smooth muscle cells more efficiently than ACE inhibitors.
May suggest distinct vascular myosin effects of AT1 blockade vs ACE inhibition in rats; leaves open human translation.
The aim of this study was to clarify the differences between the angiotensin II type 1 (AT1) receptor antagonist and the angiotensin-converting enzyme (ACE) inhibitor on smooth muscle and nonmuscle myosin heavy chain isoforms in aortic smooth muscle cells of Wistar-Kyoto rats and spontaneously hypertensive rats. All 4 myosin heavy chain isoforms are heterogeneously expressed in the smooth muscle cells of the aortic tunica media in 20-week-old rats, and the contractile-type myosin heavy chains are highly expressed in smooth muscle cells of the aortic tunica media compared with the synthetic-type myosin heavy chains. Both the AT1 receptor antagonist and the ACE inhibitor had the same effects on hemodynamics, smooth muscle cell hypertrophy and proliferation, fibrosis, and vascular remodeling in spontaneously hypertensive rats. However, the AT1 receptor antagonist had a more potent effect on the downregulation of the synthetic-type myosin heavy chains than the ACE inhibitor in spontaneously hypertensive rat aortic tunica media. In contrast, these effects of the AT1 receptor antagonist and the ACE inhibitor on hemodynamics, morphology, fibrosis, and expression of myosin heavy chain isoforms in smooth muscle cells of the aortic tunica media were not observed in Wistar-Kyoto rats. Thus, within 6 weeks, the AT1 receptor antagonist might modulate the cellular composition of myosin heavy chain isoforms in smooth muscle cells more efficiently than the ACE inhibitor, without morphological changes in the spontaneously hypertensive rat aorta.
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Fujii et al. (1999) studied Hypertension. Angiotensin II type 1 (AT1) receptor antagonist vs. Angiotensin-converting enzyme (ACE) inhibitor was evaluated on Expression of smooth muscle and nonmuscle myosin heavy chain isoforms in aortic smooth muscle cells. Within 6 weeks, the AT1 receptor antagonist downregulated synthetic-type myosin heavy chains more potently than the ACE inhibitor in spontaneously hypertensive rat aortic tunica media.
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