Beschreibung:
<jats:p>1 The receptors involved in mammalian tachykinin‐induced contractions of longitudinal smooth muscle strips of the rat gastric fundus were characterized pharmacologically.</jats:p><jats:p>2 Substance P (SP), neurokinin A, neurokinin B and senktide contracted the strips in a concentration‐dependent manner with a potency order of neurokinin A senktide > neurokinin B > substance P. The contractions were not influenced by tetrodotoxin and atropine.</jats:p><jats:p>3 L 659877, a NK<jats:sub>2B</jats:sub>‐receptor‐preferring antagonist reduced neurokinin A‐ and neurokinin B‐induced contractions (estimated p<jats:italic>K</jats:italic><jats:sub>B</jats:sub> 6.9 and 6.3, respectively) but had less pronounced effects on SP‐induced contractions and none on contractions induced by senktide. MEN 10376, an NK<jats:sub>2A</jats:sub>‐receptor‐preferring antagonist, reduced the neurokinin A‐induced contractions (estimated p<jats:italic>K</jats:italic><jats:sub>a</jats:sub> 5.2), while dactinomycin, reduced the neurokinin A‐induced contractions only to a minor extent at 10<jats:sup>−4</jats:sup> M.</jats:p><jats:p>4 CP 96345, an NK<jats:sub>1</jats:sub>‐receptor antagonist, reduced substance P‐ and neurokinin A‐induced responses, but also reduced the contractions induced by KC1 and methacholine. RP 67580, another non‐peptide NK<jats:sub>1</jats:sub>‐receptor antagonist had no effect on the substance P‐, neurokinin A‐ and neurokinin B‐induced contractions up to a concentration of 3 × 10<jats:sup>−6</jats:sup> M.</jats:p><jats:p>5 These results suggest that the mammalian tachykinins induce contractions of the longitudinal smooth muscle strip of the rat gastric fundus by direct action at muscular NK<jats:sub>2B</jats:sub>‐ and NK<jats:sub>3</jats:sub>‐receptors.</jats:p>