i don’t think it has an effect on the sodium ion levels. sweat is a form of excretion and as such, should have no significant effect on the body’s electrolyte balance.
How does sweating affect blood pressure? – Sweating will lower your systolic blood pressure because it can increase your diastolic blood pressure to compensate for the loss in fluid from evaporation by removing excess salt from your system. However, not all exercise causes you to sweat so if you are losing more than 1 litre per hour then this could be a sign that something is wrong with your heart or other systems in your body. This may indicate that you need medical attention immediately.