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Biomedical subjects

H Karppanen

Publications and source records attributed to H Karppanen.

At least 91 records · Page 5Linked to original sources
PubMed1977

Ethanol-induced changes in gastric mucosal content of cyclic AMP and ATP in the rat.

The stomach of urethane-anaesthetised rats was perfused with 10% (v/v) ethanol. At 40 min, the secretion of acid was strongly inhibited and the contents of cyclic AMP and ATP were lowered in the superficial mucosa, but not in whole gastric mucosa. After discontinuation of the ethanol perfusion, the rate of gastric acid output as well as the cyclic AMP and ATP levels recovered. Most of the acid-secreting parietal cells were found in the superficial mucosa where the changes of cyclic AMP and ATP took place. The results suggest that lowering of the mucosal contents of cyclic AMP and ATP may be involved in the ethanol-induced inhibition of the gastric acid output.

Adenosine Triphosphate↗
PubMed1977

Cyclic AMP and segmental epidural analgesia during labour.

The blood cyclic AMP level was determined just before, during and after induced labour in 27 healthy women. To achieve complete pain relief during the first stage of labour, 14 of them were given segmental epidural analgesia at the height of Th 10-12. The remaining parturients served as controls. Cyclic AMP was above the normal non-gravid level before induction in both groups. In the control group the cyclic AMP content decreased during the first stage of labour, then it increased and reached a peak at the moment of delivery. These changes were, however, not significant. In the epidural group the cyclic AMP level rose significantly during the first stage, and also reached its peak at the moment of delivery. There was a statistically significant difference between the groups at a cervical dilatation of 6-8 cm. After delivery the cyclic AMP rapidly declined to its initial value in both groups. The possible role of the decreased uterine contractions after the block in the increase of the cyclic AMP is discussed.

Adolescent↗
PubMed1976

Ethanol, indomethacin and gastric acid secretion in the rat.

In the anesthetized rat, 10% ethanol in the gastric lumen causes a total cessation of the secretion of gastric acid within 30--60 min. This effect is inhibited by pretreatment with indomethacin, which is a potent inhibitor of prostaglandin synthesis. Therefore, the inhibitory effect of local ethanol on gastric acid secretion in the rat may be mediated, at least partly, by increased synthesis of prostaglandins.

Animals↗
PubMed1976

Effects of ethanol on the cyclic AMP system of the dog gastric mucosa.

The effect of ethanol on the cyclic AMP system of the dog fundic mucosa was studied in vitro. The gastric mucosal content of cyclic AMP was increased by 2.5% ethanol, whereas 10 and 20% ethanol decreased the mucosal content of cyclic AMP. The activity of adenylate cyclase was increased by 2.5 and 5% ethanol, whereas 10% ethanol did not significantly affect it. The activity of cyclic AMP phosphodiesterase was inhibited by ethanol in a competitive manner. The increase in the gastric mucosal content of cyclic AMP, induced by low concentrations of ethanol, is apparently due to the stimulation of adenylate cyclase and inhibition of phosphodiesterase. Changes in the phosphodiesterase or adenylate cyclase activites do not explain the decrease of the mucosal content of cyclic AMP by higher concentrations of ethanol. The mechanism of the decrease is discussed.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1976

Central hypotensive effects of angiotensin II in the rat.

The floor of the fourth cerebral ventricle of urethane-anesthetized rats was exposed through the occipital foramen. Angiotensin II (10-1000 ng), applied onto the surface of the area postrema, induced a rapid lowering of the blood pressure. Pretreatment of the rats with reserpine abolished the hypotensive response to angiotensin II. It is concluded that the local application of angiotensin II induced in the vicinity of the area postrema a release of some biogenic amine, which has an inhibitory effect on the cardiovascular centres.

Angiotensin II↗
PubMed1976

Site and mode of action of clonidine in the central nervous system.

In urethane-anaesthetized rats clonidine was administered intravenously (i.v.), intracerebroventricularly (i.c.v.) or onto the surface of the area postrema which protrudes into the fourth cerebral ventricle. In each instance clonidine induced a dose-dependent lowering of the blood pressure. The region of the area postrema appears to be the most sensitive site for the action of clonidine so far studied. In order to obtain similar blood pressure effects, approximately 8 times higher amounts were needed i.c.v., and about 80 times higher amounts i.v., than onto the surface of the area postrema. A pretreatment of the rats with the specific histamine H2-receptor blocking drug, metiamide (4.5 micronmoles/rat i.c.v.) shifted the dose-response curve of clonidine (i.c.v.) to the right. The results suggest that clonidine exerts its hypotensive effect in the rat via a stimulation of histamine H2-receptors in, or in the vicinity of, the area postrema.

Animals↗
PubMed1976

The effect of electric convulsion therapy on the circulating concentrations of pituitary hormones, cortisol and cyclic adenosine monophosphate.

In order to evaluate the effect of electroconvulsive therapy on the human pituitary-adrenal function, serial plasma samples were assayed for FSH, LH, TSH, HGH, ACTH, cortisol and cyclic AMP before and after nine shocks in five subjects. A prominent finding was the rapid stimulation of the ACTH-cortisol production in all subjects, while no consistent changes in FSH, LH, TSH, HGH or cyclic AMP were found.

Adrenocorticotropic Hormone↗
PubMed1976

Effects of ethyl alcohol on the adenosine 3', 5'-monophosphate system of the human gastric mucosa.

The effect of ethyl alcohol on the cyclic AMP system of the human gastric mucosa was studied in vitro. Corporic gastric mucosa was obtained from patients operated on for gastric or duodenal ulcers. Under the in vitro conditions used, ethanol at concentrations of 5% (v/v) or less stimulated the activity of adenylate cyclase and induced a dose-dependent rise of the gastric mucosal content of cyclic AMP. However, 10% ethanol increased the activity of adenylate cyclase but did not affect the gastric mucosal content of cyclic AMP. At the concentrations of 5 or 10%, ethanol inhibited the activity of cyclic AMP phosphodiesterase in a competitive manner. Reports in the literature indicate that oral ethanol stimulates the output of gastric acid at low but not at higher concentrations. The present results are consistent with the conception that the stimulatory effect of ethanol on the output of acid is mediated by an increase of the content of cyclic AMP in the gastric mucosa.

Adenylyl Cyclases↗
PubMed1975

Plasma renin activity and in vitro synthesis of aldosterone by the adrenal glands of rats with spontaneous, renal, or pinealectomy-induced hypertension.

In the present study a comparison was made on the role of the renin-aldosterone system in rats with various forms of experimental hypertension (pinealectomy-induced, renal and spontaneous). The plasma sodium and potassium concentrations as well as renin activity were measured. The in vitro production of aldosterone by quartered adrenal glands of these rats was also determined. 5 weeks after the operations the blood pressure of the pinealectomized and renal operated rats was significantly increased. The plasma sodium concentration did not differ in various groups, but that of potassium was decreased in the renal hypertensive animals. The plasma renin activity of the pinealectomized rats was elevated while in other forms of hypertension it was at the control level. The basal aldosterone production by the adrenal quarters was equal in all the groups. ACTH, dibutyryl cyclic adenosine-3',5'-monophosphate (DBA) and 5HT stimulated the aldosterone production. The responses to ACTH and DBA were greater in the adrenals of renal hypertensive rats than in the other forms of hypertension or in the controls. We suggest that the renin-aldosterone system is of importance in the maintenance of renal hypertension, while in pinealectomy-induced hypertension elevated plasma renin activity reflects an increased sympathetic activity which probably is the main cause of hypertension in these animals.

Adenosine Monophosphate↗