Key result
A high sodium diet significantly increased angiotensin II-induced contraction of aortic rings in cold-induced hypertensive rats compared to a low sodium diet (2.39 vs. 2.21 g; p<0.01).
Why the study?
Does a high sodium diet increase vasoconstriction and AT1 receptor mRNA expression in cold-induced hypertensive rats?
Does a high sodium diet increase vasoconstriction and AT1 receptor mRNA expression in cold-induced hypertensive rats?
In a cold-induced hypertensive rat model, high sodium intake increases angiotensin II-induced vasoconstriction and AT1 receptor mRNA expression.
Hypothesis-generating in hypertensive models; leaves open translation to human sodium management.
Angiotensin II and sodium play an important pathogenetic role in several models of hypertension. Now, we investigated the effects of sodium on vasoconstriction and angiotensin II type 1 (AT1) and type 2 (AT2) receptor mRNA expression in aortic vessels from cold-induced hypertensive rats. Wistar rats on low sodium and high sodium diet were exposed to cold-stress for 8 weeks. The effects of angiotensin II infusion on mean arterial blood pressure were investigated in these rats. In addition, angiotensin II induced contraction was measured using aortic rings. Expression of AT1 receptor mRNA and AT2 receptor mRNA was assessed in aortic vessels by reverse transcription polymerase chain reaction. After infusion of angiotensin II mean arterial blood pressure in cold-induced hypertensive rats on high sodium diet was significantly higher compared to cold-induced hypertensive rats on low sodium diet (p < 0.05). Angiotensin II-induced contraction of aortic rings was significantly higher in cold-induced hypertensive rats on high sodium diet compared to cold-induced hypertensive rats on low sodium diet (2.39 +/- 0.03 g vs. 2.21 +/- 0.04 g, n = 12, p < 0.01). Angiotensin AT1 receptor mRNA was significantly higher in cold-induced hypertensive rats on high sodium diet compared to cold-induced hypertensive rats on low sodium diet (p < 0.05). It is concluded that in this nongenetic, nonsurgical animal model of cold-induced hypertension increased vasoconstriction and increased AT1 receptor mRNA expression in aortic vessels are dependent on sodium intake.
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Zhu et al. (2004) studied Cold-induced hypertension (n=12). High sodium diet vs. Low sodium diet was evaluated on Angiotensin II-induced contraction of aortic rings (p=< 0.01). A high sodium diet significantly increased angiotensin II-induced contraction of aortic rings in cold-induced hypertensive rats compared to a low sodium diet (2.39 vs. 2.21 g; p<0.01).
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