Yes. L-Arg\inine is used therapeutically up to 15 grams a day. It is a systemic vasodilator and opens up microcirculation, which increases body capacitance and reduces blood pressure. Excellent for diabetic neuropathy as well. Many people take it four or five times per day in small doses. Purchase the L-Arginine in quantity (at health food stores), rather than in capsules and you will save a lot of money. Of course you should have a home meter and check your blood pressure before and after starting with this substance, just to know the effect. The effect is not long lasting, which is one of the reasons L-Arginine is not recommended as a first line treatment for elevated blood pressure.
I would ask my physician first. Most doctors don't want you to do stuff like this on your own. "If it ain't broke don't fix it." L-Arginine should lower your Blood Pressure due to slight increase in Nitric Oxide but normally it takes about 5000 mg daily. The problem is what will that do with the beta blocker? Get your doctor's advice on this.
The answer to "ask your doctor first" usually results in a $75 charge. Many plans have a $2,000 deductible. Plus carefare and inconvenience. It is the "standard answer", however the year is 2014, and knowledge regarding L-Arginine (a vasodilator, that increases the interior diameter of the blood vessels, increasing body capacitance) and the safety thereof has been common knowledge for the last fifty years. That being said I think it would always be a good idea to ask your doctor about everything in your life. L-Arginine will do nothing to the beta blocker, except the blood pressure will be lowered slightly, which can be readily established by taking your own blood pressure. Pub med data suggests that up to 15 grams of L-Arginine may be taken daily with safety. If the blood pressure drop is significant consult your physician as to whether you can lower the dose of your beta-blocker. These days beta blockers are not the drug of choice for high blood pressure (there are exceptions). The drugs of choice are ACE inhibiters, starting with Lisinopril and if that has side effects, (usually coughing) go to Losartan. Before starting any blood pressure meds a doctor should try calcium, D3 and magnesium supplements, which will satisfactorily resolve blood pressure issues in 15-20 percent of patients, with moderate exercise and simple dietary restrictions.