PURPOSE An investigation into whether alpha(2)-adrenoceptor agonists induce contractions in the porcine ciliary arteries and to characterize the functional receptor subtype mediating these responses. METHODS Isolated arteries from the intraocular part of the porcine ciliary artery were suspended in microvascular myographs for isometric tension recording. The segments were contracted with the ...

Human isolated digital arteries and metatarsal veins, obtained postmortem, have been used to compare the effects of alpha-adrenoceptor antagonists on contractile responses to nerve stimulation. The antagonists used were prazosin, rauwolscine, BE 2254, and yohimbine. Rauwolscine (alpha 2-antagonist), as well as prazosin and BE 2254 (alpha 1-antagonists), in concentrations of 10(-9), 10(-8), and ...

β-Adrenoceptor antagonists boast a 50-year use for symptomatic control in numerous cardiovascular diseases. One might expect highly selective antagonists are available for the human βadrenoceptor subtype involved in these diseases, yet few truly β1-selective molecules exist. To address this clinical need, we re-evaluated LK 204-545 (1), a selective β1-adrenoceptor antagonist, and discovered it ...

Cerebral blood volume and intracranial pressure may be modified by influences on cerebral veins. The known adrenergic innervation of cerebral veins and their sensitivity to norepinephrine raised the question, whether pial veins can be selectively influenced through adrenoceptors in vivo. Therefore, alpha] and alpha2 adrenoceptor agonists and antagonists were locally injected into the perivascul...

Cerebral blood volume and intracranial pressure may be modified by influences on cerebral veins. The known adrenergic innervation of cerebral veins and their sensitivity to norepinephrine raised the question, whether pial veins can be selectively influenced through adrenoceptors in vivo. Therefore, alpha 1 and alpha 2 adrenoceptor agonists and antagonists were locally injected into the perivasc...

We investigated the relevance of selectivity for a given alpha-1-adrenoceptor subtype for in vivo uroselectivity of several alpha-1-adrenoceptor antagonists (alfuzosin, doxazosin, prazosin, tamsulosin, terazosin and 5-Me-urapidil). Comparison of the affinities of these alpha-1-adrenoceptor antagonists at the cloned alpha-1a, alpha-1b and alpha-1d-adrenoceptor subtypes revealed that tamsulosin a...

Acquired resistance of cancer cells to various chemotherapeutic agents is known as multidrug resistance, and remains a critical factor in the success of cancer treatment. It is necessary to develop the inhibitors for multidrug resistance. The aim of this study was to examine the effects of eight α-adrenoceptor antagonists on ABCG2/BCRP-mediated resistance and transport. Previously established H...

Human isolated digital arteries and metatarsal veins, obtained postmortem, have been used to compare the effects of a-adrenoceptor antagonists on contractile responses to nerve stimulation. The antagonists used were prazosin, rauwolscine, BE 2254, and yohimbine. Rauwolscine ((^-antagonist), as well as prazosin and BE 2254 (ati-antagonists), in concentrations of 10", 10~", and 10 mol/liter, pote...

The alpha1-adrenergic agonist phenylephrine stimulated phospholipase D (PLD) activity in Rat 1 fibroblasts transfected to express either the wild-type hamster alpha1B-adrenoceptor or a constitutively active mutant (CAM) form of this receptor. The EC50 for agonist stimulation of PLD activity was substantially lower at the CAM receptor than at the wild-type receptor as previously noted for phenyl...