in the femoral artery , the nonselective alpha adrenoceptor antagonist phentolamine ( 10 ( -6 ) m ) and the selective alpha-1 adrenoceptor antagonist prazosin ( 10 ( -8 ) and 10 ( -7 ) m ) significantly reduced the contractions induced with concentrations of thrombin greater than 6 u x ml-1 , and increased the concentration of thrombin required to produce maximal contraction .
C0034784
alpha adrenoceptor
C0001638
alpha-1 adrenoceptor