Blood Pressure Meds and Exercise

 First off the critical facts.  
I'm doing well with my band.  
I am exercising 6 days a week and just finished week 3 of the c25k program.
I'm at 7.5 on fills and am in the green zone.
I've lost since July of last year have lost 41 pounds.  Banded in November.

I've been on Atenolol (beta blocker) for 12 years through any weight.

Friday my regular dr doubled my Atenolol.  My BP is even higher now then it was 40 pounds ago.  Now this isn't shocking considering most of my family is on some form of BP meds.  But I'm only 36. I did have a heart stress test prior to surgery and all was well.

My target heart rate was max 150 - 160 running.  Today I maxed at 135.  Walking at 3.6 at a 3 incline I averaged in the 130-140's.  Today I capped at 112.

Now obviously I know it's going to come down but I want to see if anyone else has went through this.  
I was really tired after my run.  But...My BP is back to normal.

Does not hitting my targeted heart rate during exercise affect my calories lost or stamina?

I am no exercise expert but surely as you get fitter, your heart beat will get slower. So exercise which used to raise your hb to 150 will now only raise it to 130 etc..

Also, Atenelol slows hb. When i used to take it, i was told by my doc and the gym trainer that it was important NOT to raise my hb to over about 120. My doc was very specific about it.

Kate