beta 1- and beta 2-adrenergic receptors coexist in atria of humans and a variety of other species. The significance of these receptors and the quantitative extent to which beta 2-adrenergic receptors contribute to the electrophysiologic effects of catecholamines acting at beta-adrenergic receptors have not been determined. In the present study, the beta 1-selective antagonist ICI 89,406 and the...

The cutaneous circulation is used to examine vascular adrenergic function in clinical populations; however, limited studies have examined whether there are regional limb and sex differences in microvascular adrenergic responsiveness. We hypothesized that cutaneous adrenergic responsiveness would be greater in the leg compared with the arm and that these regional limb differences would be blunte...

The coronary arteries receive rich adrenergic innervation. The present study examines the effects of changes in adrenergic activity on the coronary circulation without the complicating influence of autoregulation. Diastolic and mean circumflex coronary artery pressure-flow relations were generated in conscious dogs and were described by their slope and zero-flow, pressure-axis intercept during ...

Introduction: Oxytocin is a active neuropeptide of central nervous system. In this study the effects of naloxone (opioid receptor antagonist) and yohimbine (α-2 adrenergic receptor antagonist) on analgesic effect of oxytocin applied into the locus coeruleus (LC) nucleus were investigated. Methods: Adult male Wistar rats were used. Animals divided into different groups receiving saline, oxy...

Complex sympathovagal interactions govern heart rate (HR). Activation of the postjunctional beta-adrenergic receptors on the sinus nodal cells augments the HR response to vagal stimulation, whereas exogenous activation of the presynaptic alpha-adrenergic receptors on the vagal nerve terminals attenuates vagal control of HR. Whether the alpha-adrenergic mechanism associated with cardiac postgang...

We studied 18 a-chloralose-anesthetized dogs to determine if a-adrenergic coronary vasoconstriction occurs with hindlimb static exercise. Exercise was elicited by spinal cord ventral nerve root stimulation. Regional coronary blood flow was determined by the radioactive microsphere method. Animals were studied under four experimental conditions: control rest and static exercise, rest and static ...

There is considerable evidence from our lab and others for a functional link between β-adrenergic receptor and insulin receptor signaling pathways in retina. Furthermore, we hypothesize that this link may contribute to lesions similar to diabetic retinopathy in that the loss of adrenergic input observed in diabetic retinopathy may disrupt normal anti-apoptotic insulin signaling, leading to reti...

Beta-adrenergic drugs affect lens epithelial and fiber cells. The regulation and cellular integration of lens beta-adrenergic responses are largely unknown. These studies further characterize beta-adrenergic receptors in lens cells with respect to cyclic adenosine monophosphate (cAMP) production and identification of receptor polypeptides. Stimulation of beta-adrenergic receptors in organ-cultu...

Adrenergic regulation in sleep apnea is a complex process because adrenergic physiology is difficult to summarize with one measure. Furthermore, the role of the adrenergic system in sleep apnea is often confounded with hypertension, making interpretation difficult in hypertensive apneics. Sixty-six people with and without apnea and/or hypertension (all were off antihypertensive medication) part...

Many studies have suggested that alpha-adrenergic receptors on vascular smooth muscle are heterogeneous and that both alpha 1- and alpha 2-adrenergic receptors can cause vasoconstriction when stimulated. We explored this hypothesis in normal humans by comparing the capacity of yohimbine, an alpha 2-adrenergic receptor antagonist, and prazosin, an alpha 1-adrenergic receptor agonist, with differ...