Location of α1-adrenoceptors relative to β-adrenoceptors in rat myocardium

Increased contribution of α1‐ vs. β‐adrenoceptor‐mediated inotropic response in rats with congestive heart failure

“…(2001) that the neuronal transporter for noradrenaline is down‐regulated in sympathetic nerve terminals in failing rat hearts. A lack of a correponding observation regarding the potencies of noradrenaline and phenylephrine at the α 1 ‐adrenoceptors is in concert with the observations of Dybvik et al . (1995): the β ‐adrenoceptors in the normal rat heart are located within the range of influence of uptake 1 , while the α 1 ‐adrenoceptors are located outside this influence.…”

“…Table 3). In non‐failing rat myocardium, both the potency and the efficacy of noradrenaline at the β ‐adrenoceptors are higher than at the α 1 ‐adrenoceptors (Dybvik et al . 1995, present study).…”

Concentration‐Response Relationship of α1‐Adrenoceptor‐Stimulated Increase of 86Rb+ Efflux in Rat Heart*

“…There are also several other reasons to believe that this is the case. First, phenylephrine is not a substrate for neuronal uptake mechanisms (Dybvik et al 1995). During complete 0-adrenoceptor blockade no prazosin-insensitive effect of phenylephrine has been observed.…”

Differential recruitment of α1‐ and β‐adrenoceptors in inotropic control of atrial child myocardium by endogenous noradrenaline

“…In failing ventricular myocardium from explanted human hearts the a 1 -adrenoceptor population seems to be located closer to the adrenergic nerve terminals than the b-adrenoceptor population (Skomedal et al 1998). In rat papillary myocardium, however, experimental data indicate that the a 1 -adrenoceptor population is located more distantly from the adrenergic nerve terminals than the b-adrenoceptors (Dybvik et al 1995).…”