Fukushima J. Med. Sci.,
Vol. 50, No. 2, 2004

［Original Article］

A COMPARATIVE STUDY ON CONTRACTILE RESPONSES OF
RABBIT AND GUINEA PIG VASA DEFERENTIA TO
ELECTRICAL FIELD STIMULATION

HIRONORI NAKANISHI¹⁾, SATOKO OHKUBO²⁾, TOMOYUKI ONO³⁾,
ISAO MATSUOKA³⁾ and NORIMICHI NAKAHATA²⁾

¹⁾Department of Welfare, Fukushima College for Sincerity, Fukushima
²⁾Department of Cellular Signaling, Graduate School of Pharmaceutical Science,
Tohoku University, Sendai
³⁾Department of Pharmacology, Fukushima Medical University School of Medicine, Fukushima

(Received July 8, 2004, accepted September 15, 2004)

Abstract: Contractile responses of rabbit and guinea pig vasa deferentia to electrical field stimulation (EFS) are compared.　A muscarinic receptor blocking agent, 1 mM atropine markedly reduced phasic and tonic contraction induced by EFS (20 Hz, 0.5 msec, 30 V, for 30 sec) in rabbit vas deferens, while it only slightly depressed those in guinea pig vas deferens.　Further addition of an adrenergic a₁ receptor blocking agent, 1 mM prazosin markedly depressed the second tonic contraction in both rabbit and guinea pig vasa deferentia.　In the presence of atropine and prazosin, further addition of a P2X purinoceptor desensitizing agent, 10 mM a,b-methylene ATP (a,b-MeATP) abolished the residual phasic contractile response in guinea pig vas deferens, while it partially depressed that in rabbit vas deferens.　The administration of 10 mM a,b-MeATP in the absence of atropine and prazosin markedly potentiated the phasic contractile response of rabbit vas deferens to EFS, while it depressed that of guinea pig vas deferens.　Contractile response of rabbit vas deferens to a,b-MeATP was more potent than those of ATP and 2-methyl-thioATP (2-Me-thioATP), while these nucleotides had almost same potency in guinea pig vas deferens.　These findings may indicate that contribution of cholinergic, adrenergic and purinergic neurotransmission to the contractile response of rabbit vas deferens to EFS is different from that of guinea pig vas deferens.

Key words: Rabbit vas deferens, Guinea pig vas deferens, Electrical field stimulation, Adenosine triphosphate, Norepinephrine

中西弘則，大久保聡子，小野委成，松岡　功，中畑則道

Correspondence to: Isao Matsuoka, Department of Pharmacology, Fukushima Medical University School of Medicine, Fukushima City 960-1295, Japan.
E-mail: pharm@fmu.ac.jp