Perspective on the role of P2X-purinoceptor activation in human vas deferens contractility.

The contractile actions of α,β-methylene ATP (α,β-meATP) and ATP and the effects of K(+) channel blockers in longitudinal and circular muscles of human vas deferens were investigated with a view to clarifying the functional importance of P2X(1)-purinoceptor activation and K(+) channels in modulating contractility of the tissues. The results provide an experiment-based perspective for resolving differing reports on purinergic activation of the tissues and uncertain roles of large-conductance Ca(2+)-activated K(+) (BK(Ca)) and voltage-gated delayed rectifier K(+) (K(V)) channels. α,β-Methylene ATP (3-100 μm) evoked suramin-sensitive contractions of longitudinal muscle but rarely of circular muscle.

Comparative effects of T-type and L-type Ca(2+)-antagonists against noradrenaline-induced contractions of human vas deferens.

Objective: To investigate the effects of the relatively selective T-type Ca(2+)-antagonists, mibefradil and flunarizine, and the L-type Ca(2+)-antagonist, nifedipine, on the contractions of longitudinal and circular muscles of human vas deferens, to elucidate the possible involvement of T-type voltage-gated Ca(2+) channels (VOCs) in the contractile function of the tissue.

Materials And Methods: Human vas deferens specimens from elective vasectomies were cut into strips of longitudinal muscle or transversely into rings of circular muscle. These were set up for tension recording and superfused with Krebs' medium (36 degrees C).

Contractile actions of L-type Ca2+ agonists in human vas deferens and effects of structurally different Ca2+ antagonists.

The actions of L-type Ca(2+) agonists, FPL 64176 and Bay K 8644 were investigated in human vas deferens in the presence of structurally different L-type Ca(2+) antagonists. The L-type Ca(2+) agonists (or=20 min) evoked only rhythmic contractility even in moderately depolarizing ([K(+)](o), 10mM) medium.

Contractile actions of imidazoline alpha-adrenoceptor agonists and effects of noncompetitive alpha1-adrenoceptor antagonists in human vas deferens.

The contractile actions of imidazoline alpha-adrenoceptor agonists were investigated in human vas deferens longitudinal and circular muscle. The effects of phenoxybenzamine were studied in comparison to dibenamine and SZL-49 (4-amino-6,7-dimethoxy-2-quinazolinyl-4-(2-bicyclo[2,2,2]octa-2,5-dienylcarbonyl-2-piperazine), an alkylating prazosin analogue that discriminates between alpha(1H)- and alpha(1L)-adrenoceptor subtypes. The imidazoline alpha-adrenoceptor agonist, A-61603 (N-[5-(4,5-dihydro-1H-imidazol-2yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl]methanesulfonamide hydrobromide), was a potent agonist (pD(2); longitudinal muscle 6.

Discrimination by SZL49 between contractions evoked by noradrenaline in longitudinal and circular muscle of human vas deferens.

The effects of irreversible alpha1-adrenoceptor antagonists, SZL-49 (an alkylating analogue of prazosin), dibenamine and benextramine on contractions to noradrenaline (NA) in longitudinal and circular muscle of human epididymal vas deferens were investigated. Competitive alpha1-adrenoceptor antagonists were also used to further characterize the alpha1-adrenoceptor subtype stimulated by NA in longitudinal and circular muscle. NA evoked concentration-dependent contractions of both muscle types (pD2; 5.