The methods can be used to monitor {TAIL ~ the effects} of added external agents on {HEAD ~ cellular membrane potential} 
The methods can be used to monitor { TAIL ~ the effects } of added external agents on { HEAD ~ cellular membrane potential }
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD