Hello,
Something very simple which you can use to change capacitance, resistance, and inductance is have a voltage(or current) controlled resistor/inductor/capacitor. Passing a voltage thourgh the blocks will change these variable loads as you wish (you can set it anything like 12.5kohms per Volt for example). You can find these components under Basic-Virtual in the Basic Group. Hope this helps.
Kind Regards,
Miguel V
National Instruments