What is the Role of “Obamacare” in Driving Down HealthCare Costs?

I’ve been doing a lot of reading regarding healthcare pricing in the U.S. relative to the costs paid for the same medical services or goods in European countries, or even the amounts paid by those on Medicare or Medicaid.

The term ‘chargemaster’ refers to the complete pricing list of every product or service billed for by a medical provider such as a hospital.

What, if anything, is Obamacare doing to gain more control of the actual pricing of medical services, and has Obamacare been able to successfully negotiate lower costs with providers for medical services than those typically negotiated between insurers and medical providers though non-Obamacare health plans?

Beyond a simple answer, if you are able to direct me to any specific reference materials or resources that address this I would appreciate that, as I suspect others may be interested in this also.