Identification of serotonergic (5HT1A-type) receptors in broiler small intestine by application of serotonin and its agonists and antagonists

Serotonin or 5-hydroxytryptamine (5-HT), is a monoamine neurotransmitter synthesised from L-tryptophan in serotonergic neurons and enterochromaffin cells of the gastrointestinal tract. This neurotransmitter is widely distributed in the animal and plant kingdom and regulates some central and peripheral functions through several types of specific serotonergic (5-HT) receptors. Since it is known that the effect of serotonin, especially in pathological conditions, is very important, we believe that determining the types of receptors for this substance would make it possible to use their agonist or antagonists, which would undoubtedly enhance the pharmacotherapy of functional disruption of the small intestine in broilers. Investigations were carried out on isolated smooth muscle strips of the circular and longitudinal layer of the broiler small intestine (strip dimension 3-4 mm x 2 cm). The muscle strips were placed in an isolated organ bath. The mechanical activity of the preparations was recorded via an isotonic force transducer coupled to a pen recorder. This was done following the addition of serotonin (nonselective 5-HT agonist), 8-OH-DPAT (selective 5-HT1A agonist) and spiroxatrin (selective 5-HT1A antagonist). The sensitivity of the tissues to acetylcholine was tested before starting the experiments. Using the obtained results, it can be concluded that 5HT1A type receptors are present in smooth muscles of the broiler small intestine, duodenum and ileum, especially in the longitudinal smooth muscle layer which reacted with contractions even to low serotonin concentration (10-6), but not in the jejunum.

Identification of histaminic (H1-type) receptors in small intestine of broilers by application of histamine and some of its agonists and antagonists

Histamine is a biologically active amine (biogenic amine) that has a broad spectra of physiologic and pathologic reactions in the organism. Its effects are shown through 4 types of specific receptors (H1, H2, H3 and H4). Histamine is one of the main causes of intestine disorders and the occurrence of diarrhea, both of which are very common in broilers. Whilst there is no information in scientific literature about the presence of histaminic receptors in smooth muscles of the small intestine wall of broilers (duodenum, jejunum and ileum), we tried to determine their presence, distribution and type in this kind of muscles. Investigations were carried out on isolated smooth muscles of the circular and longitudinal layer of the broiler small intestine (strip dimension 3-4 mm x 2 cm). The muscle strip was then placed in an isolated organ bath and the contractions obtained were registered with isometric transducers on a two-channel printer. This was done following the addition of histamine, betahistine (H1 agonist), and mepiramine (H1 antagonist). Muscle vitality was checked by adding acethylcholine chloride. Using the obtained results, it can be concluded that H1 types of histaminergic receptors are present in smooth muscles of the small intestine of broilers. .

The effects of targeted deletion of the aromatase enzyme on prostatic contractile responses to noradrenaline in mice

This investigation aimed to see whether a change in the oestrogen to androgen ratio alters prostate contractility. Isolated organ bath studies using prostates from aromatase knockout (ArKO) mice which were homozygous (ArKO−/−) and heterozygous (ArKO+/−) for the disrupted aromatase cyp19 gene and wild-type littermates (ArKO+/+) were conducted. The distribution of noradrenergic nerves was visualized using the sucrose–potassium phosphate–glyoxylic acid method. ArKO−/− mice had increased prostate weights compared with ArKO+/+ mice. Frequency–response curves to electrical field stimulation (EFS; 0.5 ms pulse duration, 60 V, 0.1–20 Hz) yielded frequency-dependent contractions, while noradrenaline (10 nM–1 mM) and tyramine (1 μM–1 mM) produced concentration-dependent contractions. Prazosin (0.3 μM) attenuated the responses induced by noradrenaline and EFS in all mice (P≤0.019, n=5–7), while cocaine (10 μM) attenuated the responses evoked by tyramine (P<0.001, n=6). There were no genotype differences in EFS- and noradrenaline-induced responses (P≥0.506, n=10–13). Prostates from ArKO−/− and ArKO+/− mice were more sensitive to tyramine than prostates from ArKO+/+ mice (P<0.001, n=11–13). Dense adrenergic innervation of the prostate was similar in all mice. These results suggest that although the absence of aromatase increases prostatic growth, this translates only to a subtle and selective increase in contractility in mature mice.

Effect of linsidomine on the human radial artery

The response of the human radial artery to a direct NO donor, linsidomine or 3-morpholino-sydnonimine (Sin 1), in the therapeutic management of peri-operative spasm may increase the patency rates of these grafts in the short, medium and long term. Evaluation of the effects of Sin 1 on the human radial artery is of even greater interest as it has not been published previously. Ninety-six human radial artery rings were studied with two protocols. Rings were mounted in an isolated organ bath between two stainless steel metallic rods connected to stress gauges. Protocol 1 studied the vasorelaxant effect of Sin 1 and nitroglycerin (TNT). Protocol 2 studied the reactivity of the radial artery to the vasoconstrictor agents arginine vasopressin (AVP) and angiotensin II (ANG II). The vasorelaxant effect of Sin 1 on the human radial artery was comparable with that of TNT, but with no tolerance effect. After Sin 1 pre-incubation, the vasoconstrictor effect of ANG II was abolished, whereas AVP induced maximum vasoconstriction similar to that of the control (not statistically significant), but with a shift in the EC50 to higher concentrations, EC50 = 15±20nM. Sin 1 vasorelaxation of rings precontracted by ANG II was maximal, whereas after contraction by AVP, relaxation remained less than 70%; Sin 1 is a potent vasorelaxant on the human radial artery, which does not exhibit cross-tolerance with nitrates. This compound may be used pre- or post-operatively, and would undoubtedly be of benefit in the peri-operative preparation bath.

Convenient apparatus for recording contractions of isolated heart muscle

A simple and convenient apparatus for physiological or pharmacological experiments on preparations of isolated heart muscle is described. Provision is made for recording independently from two preparations mounted in the same bath. Electrodes for stimulation or recording are incorporated in the clamps that hold the tissue. The construction ensures the maintenance of a high oxygen tension at the surface of the tissue without the mechanical artifacts that result from bubbling oxygen directly past it. papillary muscle; isolated organ bath; isolated atria; double muscle preparation; circulating salt solution; stimulating electrodes; concentration-effect curves; inotropic and chronotropic effects; oxygenation Submitted on November 5, 1964