**6. Radiotelemetry to study gene × environment in hypertension – Experience from our laboratory**

Hypertension is an important contributor of mortality and morbidity in humans. Our understanding of the aetiology of the disease is incomplete and the search for the genetic determinants is complicated by the fact that blood pressure is very labile, with important changes occurring within seconds and minutes. As we have shown, blood pressure is hard to assess reproducibly without bias when performing epidemiological studies or GWAS. These problems are in part due to the important environmental component modulating blood pressure. Among these environmental modulators, psychogenic stress exerts a major influence. In experimental research using rodents, we have shown that the usual tail-cuff method for blood pressure determination induces stress and increases body temperature, two major modulators of blood pressure and hypertension. Therefore, we think that telemetry is the only technique to ascertain blood pressure with the least amount of bias. It is also the only technique allowing the measurement of the stress component modulating blood pressure. The few examples below will try to illustrate the level of refinement and robustness that can be achieved in hypertension research when the environmental influences are understood and telemetry the method employed for assessing blood pressure.
