Key result
In salt-loaded rats neonatally treated with capsaicin, both candesartan and PD 123319 attenuated the development of hypertension (P<0.05), indicating AT1 and AT2 receptor involvement.
Why the study?
Do AT1 and AT2 receptor antagonists reduce blood pressure in a rat model of salt-sensitive hypertension induced by sensory nerve degeneration?
Do AT1 and AT2 receptor antagonists reduce blood pressure in a rat model of salt-sensitive hypertension induced by sensory nerve degeneration?
p-value: p=<0.05
Both AT1 and AT2 receptors contribute to the development of salt-sensitive hypertension in rats with sensory nerve degeneration, as blockade of either receptor attenuates blood pressure increases.
No direct clinical implications; leaves open translation of AT1/AT2 roles to human salt-sensitive hypertension.
OBJECTIVE: To define the role of the type 1 angiotensin II (AT1) and type II (AT2) receptors in the development of salt-sensitive hypertension induced by sensory nerve degeneration. DESIGN AND METHODS: Neonatal Wistar rats were given capsaicin 50 mg/kg s.c. on the first and second days of life. After weaning, male rats were divided into six groups and treated for 3 weeks with: control + high sodium diet (4%, CON-HS), capsaicin pretreatment + normal sodium diet (0.5%, CAP-NS), CAP-HS, CAP + HS + candesartan (10 mg/kg per day) (CAP-HS-CAN), CAP + HS + PD 123319 (30 mg/kg per day) (CAP-HS-PD), and capsaicin pretreatment + high sodium diet + candesartan + PD 123319 (CAP-HS-CAN-PD). Mean arterial pressure (MAP) was measured by carotid arterial catheterization. Urinary Na+ concentrations were determined by using a flame atomic absorption spectrophotometer. Levels of calcitonin gene-related peptide (CGRP) in dorsal root ganglia (DRG) and plasma renin activity (PRA) were determined by radioimmunoassay. RESULTS: CGRP contents in DRG were decreased by capsaicin (P < 0.05). MAP was higher in CAP-HS rats compared with all the other groups (P < 0.05). The 24 h urine and sodium excretion increased when a high salt diet was given, but they were lower in CAP-HS and CAP-HS-CAN than in CON-HS (P < 0.05). PRA was suppressed in CON-HS and CAP-HS compared with CAP-NS, but it was higher in CAP-HS than in CON-HS (P < 0.05). CONCLUSION: Insufficiently suppressed PRA by high salt intake may contribute to increased salt sensitivity and account for effectiveness of candesartan in lowering blood pressure in this model. Furthermore, PD 123319 attenuates the development of hypertension in salt-loaded rats neonatally treated with capsaicin, indicating that the AT2 receptor contributes to the increase in blood pressure.
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Huang et al. (2001) studied Salt-sensitive hypertension induced by sensory nerve degeneration. Candesartan and/or PD 123319 vs. Control + high sodium diet, capsaicin + normal sodium diet, capsaicin + high sodium diet was evaluated on Mean arterial pressure (MAP) (p=<0.05). In salt-loaded rats neonatally treated with capsaicin, both candesartan and PD 123319 attenuated the development of hypertension (P<0.05), indicating AT1 and AT2 receptor involvement.
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