CHS Pathophysiology of Hypertension 3 — Questions and Answers
Question 1: Vascular remodeling in chronic hypertension involves which structural change in resistance arteries?
- Decreased media-to-lumen ratio with normal wall thickness
- Inward eutrophic remodeling with increased media-to-lumen ratio and reduced lumen diameter (Correct answer)
- Outward hypertrophic remodeling with increased lumen diameter
- Loss of smooth muscle cells with fibrosis only
Correct answer: Inward eutrophic remodeling with increased media-to-lumen ratio and reduced lumen diameter
Inward eutrophic remodeling, characterized by rearrangement of existing material around a smaller lumen without increased cell mass, increases the media-to-lumen ratio and vascular resistance in essential hypertension.
Question 2: Reactive oxygen species (ROS) contribute to hypertension by which of the following mechanisms?
- Increasing nitric oxide synthesis from eNOS
- Scavenging nitric oxide to form peroxynitrite, reducing vasodilatory capacity (Correct answer)
- Inhibiting angiotensin II signaling
- Decreasing vascular smooth muscle calcium sensitivity
Correct answer: Scavenging nitric oxide to form peroxynitrite, reducing vasodilatory capacity
Superoxide anion rapidly reacts with nitric oxide to form peroxynitrite, reducing NO bioavailability and impairing endothelium-dependent vasodilation, a key mechanism of oxidative stress in hypertension.
Question 3: Which enzyme is a major source of superoxide production in vascular tissue in hypertensive patients?
- Xanthine oxidase and NADPH oxidase (Correct answer)
- Catalase
- Glutathione peroxidase
- eNOS (when fully functional)
Correct answer: Xanthine oxidase and NADPH oxidase
NADPH oxidase (particularly Nox1, Nox2, Nox4) and xanthine oxidase are the principal sources of vascular superoxide in hypertension, driving oxidative stress and endothelial dysfunction.
Question 4: Chronic low-grade inflammation in hypertension is evidenced by elevated levels of which biomarker that also independently predicts cardiovascular risk?
- Serum albumin
- High-sensitivity C-reactive protein (hsCRP) (Correct answer)
- Serum creatinine
- Brain natriuretic peptide (BNP)
Correct answer: High-sensitivity C-reactive protein (hsCRP)
Elevated hsCRP reflects vascular inflammation and is associated with endothelial dysfunction, oxidative stress, and increased cardiovascular risk in hypertensive patients.
Question 5: The concept of 'autoregulation' in the kidney explains which phenomenon relevant to hypertension?
- The kidney's ability to maintain constant glomerular filtration rate despite changes in perfusion pressure (Correct answer)
- Spontaneous regulation of renin release independent of blood pressure
- The autonomic control of renal vasomotor tone
- Tubuloglomerular feedback inhibition of renin
Correct answer: The kidney's ability to maintain constant glomerular filtration rate despite changes in perfusion pressure
Renal autoregulation maintains relatively constant GFR and renal blood flow over a wide range of perfusion pressures through myogenic and tubuloglomerular feedback mechanisms, protecting glomeruli from barotrauma.
Question 6: T-lymphocyte infiltration into the kidneys and vasculature in experimental hypertension models supports which pathophysiological concept?
- Autoimmune destruction of baroreceptors
- Immune-mediated inflammation as a contributor to, not just a consequence of, hypertension (Correct answer)
- T-cells directly produce renin
- Adaptive immunity lowers blood pressure via cytokine production
Correct answer: Immune-mediated inflammation as a contributor to, not just a consequence of, hypertension
Studies showing that RAG-1 knockout mice (lacking T and B cells) have blunted hypertensive responses and that adoptive transfer of activated T cells restores hypertension demonstrate an active role for adaptive immunity in blood pressure elevation.
Question 7: Arterial stiffness, measured by pulse wave velocity (PWV), increases blood pressure by which hemodynamic mechanism?
- Decreasing diastolic pressure and increasing pulse pressure, which raises systolic BP (Correct answer)
- Increasing peripheral resistance only
- Reducing cardiac output
- Lowering mean arterial pressure
Correct answer: Decreasing diastolic pressure and increasing pulse pressure, which raises systolic BP
Stiff arteries reduce the Windkessel buffering effect, causing faster wave reflection that augments systolic pressure and lowers diastolic pressure, thereby increasing pulse pressure — a hallmark of isolated systolic hypertension in the elderly.
CHS Pathophysiology of Hypertension 3
Vascular remodeling in chronic hypertension involves which structural change in resistance arteries?