It is known that even with small muscle work, blood pressure rises. According to one hypothesis, this happens because

It is known that even with small muscle work, blood pressure rises. According to one hypothesis, this happens because the working muscles release into the blood some substances that affect the blood vessels, according to another hypothesis, when the brain sends signals to the muscles that make them work, it simultaneously sends signals to the vessels that change blood pressure. What experiments should be done to test these hypotheses?

The brain takes part in the performance of any motor acts. It always sends signals to muscle fibers, whether it be a conscious movement or not. Therefore, in order to test the first hypothesis – about the release of substances that cause vasoconstriction – it is necessary to “trick” the brain and cause muscle contraction without its participation. This is easily done with the help of an external stimulus – electric shock. A light electrical current will cause the muscles to contract involuntarily. If at this moment vasoconstriction occurs (pressure increases), then, therefore, this is caused by substances secreted by the muscles.

But this will not give us confidence that the contraction of blood vessels is caused by chemicals. It is necessary to take a blood sample BEFORE and AFTER the contraction, and then compare it for the chemical composition. If new substances are found, then, consequently, the first hypothesis turns out to be more reliable.

To test the second hypothesis – that the brain sends signals in parallel to the vessels, causing them to contract – you just need to block the transmission of electrical signals from the brain to the muscles. If, when trying to perform a movement, the vessels contract, then, consequently, they are caused by signals that are part of the signal of the motor program.