PubMed Health⌕ Search

Biomedical subjects

A Stoll

Publications and source records attributed to A Stoll.

29 records · Page 2Linked to original sources
PubMed1991

5-HT1-like receptors mediate 5-hydroxytryptamine-induced contraction of guinea-pig isolated iliac artery.

1. The effects of 5-hydroxytryptamine (5-HT) and of the 5-HT1-like receptor agonists, 5-carboxamidotryptamine (5-CT) and sumatriptan (GR43175) were investigated in isolated ring preparations of guinea-pig common iliac artery. 2. The three agonists induced very weak, if any, contractions of unstimulated preparations, whereas they elicited concentration-dependent contractions in preparations given a moderate tone by a threshold concentration of prostaglandin F2 alpha (PGF2 alpha). 3. Under the latter conditions, Emax values for 5-HT and 5-CT reached about 45% of PGF2 alpha maximal effect, whereas the Emax value of sumatriptan was significantly lower (about 35%). The rank order of potency (mean EC50 value, nM) was 5-CT (6.6) greater than 5-HT (22.9) greater than sumatriptan (155). Pargyline, cocaine or deoxycorticosterone were without significant effect on the contractions induced by 5-HT. 4. The 5-HT3 receptor antagonist, (1 alpha H, 3 alpha,5 alpha H-tropan-3-yl) 1-H-indole-3-carboxylic acid ester (ICS 205-930; 1 microM), had no effect on 5-HT-, 5-CT- and sumatriptan-induced contractions. 5. The 5-HT2 receptor antagonist, ketanserin (1 microM) caused only small rightward shifts (concentration-ratios, about 2) in the concentration-response curves to 5-HT, 5-CT and sumatriptan without significantly depressing the maximum effects. 6. In the presence of ketanserin (1 microM), the non-selective 5-HT receptor antagonist, methiothepin (0.1 microM), shifted the concentration-response curves to 5-HT and 5-CT to the right in a parallel manner and to a similar extent for both agonists (respective mean pKB values, 8.07 and 8.27). The effect of sumatriptan was also antagonized by methiothepin, but solvent effects precluded quantitative analysis of this antagonism. 7. It is concluded that 5-HT1-like receptors mediate the contractions induced by 5-HT, 5-CT and sumatriptan in guinea-pig isolated iliac artery. For reasons not yet understood, these receptors are detected only when the tissues are moderately pre-contracted by PGF2alpha.

Animals↗
PubMed1984

Effect of age on behavioral responses and tissue levels of apomorphine in the rat.

Rats of several ages between 2 and 24 months were tested for stereotyped behavioral responses to R(-)apomorphine-HCl (APO), a potent and selective dopamine agonist. Between 2 and 24 months, the ED50 for apomorphine decreased 2.5-fold (0.14-0.06 mg/kg, i.p.), as assessed by a microcomputer-assisted technique. Not only were older rats more sensitive to apomorphine, but the duration of the behavioral effects increased with age and showed a greater change at doses which were greater than the ED50. When levels of apomorphine in brain were assayed by liquid chromatography and electrochemical detection, there was a progressive increase in peak levels of the agent in the tissue as well as a delay in its elimination from brain, with increasing age. Moreover, there was a highly significant correlation between increased behavioral effect and the level of apomorphine in brain with increasing age (r greater than 0.8). These results indicate that increased levels in brain or decreased elimination of apomorphine may be an important factor contributing to a marked increase in behavioral sensitivity to apomorphine with age in the rat.

Aging↗
PubMed1982

Tissue levels of N-n-propylnorapomorphine after treatment with (-)10,11-methylenedioxy-N-n-propylnoraporphine, an orally long-acting prodrug active at central dopamine receptors.

High performance liquid chromatography with electrochemical detection was used to assay N-n-propylnorapomorphine (NPA) and other aporphines. Pretreatment of rats with (-)10,11-methylenedioxy-N-n-propylnoraporphine (MDO-NPA) yielded dose-dependent increases in tissue levels of NPA after oral or parenteral administration. Cerebral levels of NPA significantly paralleled the stereo-typed behavioral effects produced by MDO-NPA at several doses and times. Pretreatment with the microsomal oxidase inhibitor SKF-525A (see Methods) prevented these behavioral effects of MDO-NPA and blocked the formation of NPA in vitro. These results support the suggestion that MDO-NPA is a uniquely orally effective and relatively long-acting aporphine which acts at cerebral dopamine receptors as a prodrug of NPA.

Animals↗
PubMedDate not supplied

Nortriptyline plasma levels and clinical response in patients with familial pure unipolar depression and blunted TRH tests.

We studied the efficacy of nortriptyline (NT) when given in doses which produce tricyclic antidepressant (TCA) levels within the proposed therapeutic "window" in a select patient group to assess the "window" hypothesis in a group of patients that was biologically homogeneous with respect to the TRH test and clinically homogeneous with respect to RDC, DSM III, and Winokur criteria. Pharmacokinetic and dose differences were controlled for by administering a NT dose-prediction test, giving the indicated dose, allowing levels to reach steady state and changing the dose, if necessary, to maintain NT levels within the range of 90-130 ng/ml. Using this protocol nine of ten patients responded to NT. This rate of response for a severely depressed patient group is comparable to response data for ECT and recent European data using regular NT levels to change doses of NT and assess appropriate NT trial duration.

Adult↗