Hi eureka, I think I have seen you over in the PD site. Welcome to the heart forum. I have MSA and Multiple Sclerosis. My MSA (multiple system atrophy) has been dx'ed since feb of this year but started in august of last year with symptoms of low heart rate and extremely low blood pressure to the point where I pass out when I stand. I even have seizures when my blood pressure gets low. I take two different medications Promatine and Florinef to keep my BP up and most times it works but sometimes it does drop for no cause at all. It is quite frustrating and daunting. Gatorade is a good source of sodium as is salt added to the diet but this adds fluid retention and can constrict the blood vessels. Parkinson's disease does have a common factor problem of low blood pressure. Here are some links for you to check out, webmd has some excellent resources on parkinson's disease and low blood pressure as does healing well. These are just a few I have pull for you. Please do keep us up dated on how he is doing. Take care and our thoughts are with you both.
http://www.ohsu.edu/pco/pdf_docs/handbook_low_bloodpressure.pdf
http://www.webmd.com/content/article/51/40655.htm