Diagnostic ultrasound irradiation combined with microbubbles to modulate carotid body activity for the treatment of obesity-related hypertension in rabbits.

BACKGROUND

Carotid body (CB) ablation can reduce sympathetic activity and blood pressure but impair the body's ability to regulate hypoxia. This study explores the efficacy and safety of using microbubble contrast agents combined with high mechanical index diagnostic ultrasound irradiation (HMIUI) to modulate CB activity in treatment of hypertension in rabbits.

METHODS

Obese hypertensive rabbits were randomly divided into three groups: unilateral intervention group (UIG, n = 6), bilateral intervention group (BIG, n = 10), and control group (CG, n = 7). Rabbits received intravenous injection of sulfur hexafluoride microbubbles for 15 min, and irradiation at the carotid bifurcation by continuous diagnostic ultrasound FLASH mode simultaneously. Blood pressure (BP), hypoxic ventilatory response (HVR), peripheral chemoreceptor sensitivity (PCS), and baroreceptor sensitivity (BRS) were measured, and values were compared with before the intervention and 1 month after. In addition, pathology and electron microscopy were used to observe the histological and ultrastructural changes of CB.

RESULTS

In both UIG and BIG groups, systolic and diastolic blood pressure significantly decreased compared to pre-intervention (p < 0.05). Compared to the control group, the BIG group showed a decrease of 10 mmHg exceeding in systolic and diastolic blood pressures. HVR and PCS decreased by nearly 50% from pre-intervention. Changes in CB injury and fibrous tissue proliferation were found by Histological. TUNEL assay showed varying degrees of apoptosis in the treated CB, and immunofluorescence confirmed the reducing expression of type I and II cells.

CONCLUSIONS

Ultrasound microbubbles combined with HMIUI effectively modulate CB function and reduce blood pressure in an obese hypertensive rabbit model in the short term.