No colocalization of immunoreactivities for VIP and neuronal NOS, and a differential relation to cGMP-immunoreactivity in bovine penile smooth muscle.

The distribution of immunoreactivity (IR) for the neuropeptide vasoactive intestinal polypeptide (VIP) and neuronal nitric oxide synthase (nNOS) in the bovine retractor penis muscle (RP) and penile artery (PA) was studied by using two different methods. The distribution of these immunoreactivities was also compared with that of the immunoreactivity for cyclic guanosine monophosphate (cGMP). In both tissues the nerve fibers and terminals immunoreactive for VIP had a distribution that was completely different from that of the nerve fibers and terminals immunoreactive for nNOS.

The endothelin ET(B) receptor agonist [125I]BQ-3020 binds predominantly to nerves in the bovine retractor penis muscle and penile artery.

Preliminary pharmacological experiments have suggested that in the bovine retractor penis muscle there are relaxation-mediating endothelin ET(B) receptors, at least part of which are located on the inhibitory nitrergic nerves. The present work was undertaken to test this hypothesis by means of receptor autoradiography and additional pharmacological experiments. In the retractor penis muscle and the penile artery, specific binding of the ETB receptor-selective agonist [125I]BQ-3020 took place predominantly to nerve trunks and minor nerve branches.

Functional characterization of endothelin receptors in the bovine retractor penis muscle and penile artery.

The effects of endothelin-1 and sarafotoxin 6c on the bovine retractor penis muscle and the bovine penile artery were studied, and a functional characterization of endothelin receptors in these tissues was performed by using the ETA-receptor antagonist BQ-123 and the ETB-receptor antagonist IRL 1038. The retractor penis muscle and the penile artery were about equipotently contracted by endothelin-1 in a concentration-dependent manner the EC50 values being 3.5 x 10(-9) M and 1.

Relaxation of the bovine retractor penis muscle by a small K+ excess and the role of K+ in its neurogenic relaxation.

The mechanism of the relaxation of the bovine retractor penis muscle induced by 6.7 mM K+ as well as the role of K+ in the neurogenic relaxation of this muscle induced by nicotine, acetylcholine or electrical field stimulation, was studied. The relaxation induced by 6.

The use of the bovine retractor penis muscle for the assessment of ganglion-blocking activity of neuromuscular blocking and other drugs.

Inhibition of relaxation of strips of the bovine retractor penis muscle induced by a standard dose of nicotine (30 microM) was used for quantitative assessment of the ganglion-blocking activity of eight neuromuscular blocking agents that are in clinical use. The order of potency of the drugs studied was (+)-tubocurarine >> alcuronium > vecuronium > metocurine >> pancuronium > atracurium >>> suxamethonium > gallamine. The results have been compared to those obtained with other methods.