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Biomedical subjects

M Hammarström

Publications and source records attributed to M Hammarström.

29 records · Page 2Linked to original sources
PubMed1989

Autonomic nervous control of cervical secretion in the guinea-pig.

Neurogenic influence on cervical secretion was studied in experiments performed on isolated guinea-pig cervix with intact adjacent nerves. The secretion was estimated as carbohydrate efflux. Experiments were undertaken at ovulation time when secretion is most prominent. Hypogastric nerve stimulation significantly increased carbohydrate release. This response was unaffected by phentolamine but inhibited by TTX, scopolamine and hexamethonium, as well as previous destruction of paracervical ganglia. Pelvic nerve stimulation did not affect cervical secretion. Carbachol as well as VIP induced a secretory response of the same extent as did hypogastric nerve stimulation. Scopolamine abolished the VIP-induced secretion. VIP and carbachol in combination had no additive effect. It is concluded that cervical glands of the guinea-pig uterus possess a cholinergic secretomotor innervation. The main pathway is the hypogastric nerve and neurons have a peripheral relay at paracervical ganglia. A more complex peripheral organization cannot be excluded.

Animals↗
PubMed1986

Comparison between the conventional Malmström extractor and a new extractor with Silastic cup.

One hundred women for whom instrumental delivery had to be performed due to fetal asphyxia or uterine inertia were randomized to a vacuum extraction with the conventional Malmström instrument or the Silastic cup of Kobayashi. With the Silastic cup, extraction time was shorter and injuries to the scalp were less common. On the other hand, extraction with the Silastic cup failed more often, especially in occiput posterior position. There were no differences in Apgar scores between the two groups.

Clinical Trials as Topic↗
PubMed1985

Reduced uptake of noradrenaline into storage vesicles from the pregnant uterus.

A noradrenaline (NA) storage vesicle fraction was isolated from the uteri of virgin as well as pregnant guinea-pigs. The uptake of 3H-NA into respective vesicle fractions was compared. Total uptake of 3H-NA in the presence of Mg2+ (2.5mM) and ATP (2.5 mM) at 30 degrees C after 20 min was 6.0 +/- 1.4 pmol . mg-1 in uterus fractions from virgin guinea-pigs as compared to 1.87 +/- 0.41 pmol . mg-1 in uterus fractions from pregnant animals. When desipramine (5mM) was added in order to block neuronal uptake the corresponding figures were 4.75 +/- 0.92 and 0.51 +/- 0.18 pmol . mg-1, respectively. Thus in the presence of desipramine (5mM) uptake was reduced by 21.4% in fractions from virgin uteri but by 72.7% in fractions from pregnant uteri. Reserpine (0.1 microM) inhibited uptake of 3H-NA by 34% in fractions from virgin uteri and by 46% in fractions from pregnant uteri. Our results indicate a decreased amount of functional storage vesicles in uteri of guinea-pigs at term pregnancy and are consistent with the proposed degeneration of adrenergic nerves during pregnancy.

Adenosine Triphosphate↗
PubMed1985

Autonomic nervous control of endometrial secretion in the guinea pig.

Secretory responses of the guinea pig endometrium to field stimulation of nerves and/or drugs were studied throughout oestrous cycle. Secretory responses are dependent on the hormonal state of the animals and are seen at oestrus, metoestrus and at implantation time. The cholinergic nature of the secretory innervation was confirmed. Optimal secretory response was found at 0.5 or 1 Hz continuous stimulation. Adrenergic inhibition was revealed at metoestrus (day 3-5), The alpha-adrenergic inhibitory influence had its optimal frequency at 0.5 Hz. The inhibition seemed to be both prejunctional and postjunctional. VIP increased endometrial secretion, the effect was probably preterminal. Burst stimulation at any frequency gave less (or no) secretory responses under these experimental conditions. The complex organization of the endometrial innervation is apparent.

Adrenergic alpha-Antagonists↗
PubMed1984

Intimacy of the neuroeffector junction and resistance to alpha-adrenoceptor-blockade of the neurogenic contractile response in vasa deferentia from guinea pig and rat.

The effect of phentolamine on the neurogenic contractile response in vasa deferentia from rat and guinea pig was studied during Wallerian degeneration. This response was also investigated after partial denervation (surgery or chemical sympathectomy by guanethidine treatment) in vasa deferentia from guinea pig. During Wallerian degeneration the response showed a gradual increase in sensitivity to phentolamine and was abolished in the late stages. The neurogenic contractile response of the partially denervated vas deferens was blocked by low concentrations of phentolamine. It is concluded that decreased intimacy of the neuroeffector junctions leads to increased susceptibility to alpha-adrenoceptor blockade of the contractile response to nerve stimulation. It is further concluded that the motor transmission in the vas deferens is essentially adrenergic. The resistance to alpha-adrenoceptor blockade of the initial phase of the contractile response to nerve stimulation of intact vasa deferentia from guinea pig and rat might well be explained by the "proximity theory" of Dale & Gaddum although participation of supplementary mediators cannot be excluded.

Adrenergic alpha-Antagonists↗
PubMed1984

Comments on the atropine resistance of the neurogenic contractile response of the rat detrusor muscle.

The resistance to atropine or scopolamine of the neurogenic contractile response to field stimulation of intramural nerves of the rat detrusor was studied during the early phase of Wallerian degeneration in vitro and in vivo. The neurogenic contractile response to low frequency stimulation of control bladders was completely resistant to atropine or scopolamine in vitro. As a matter of fact the response was enchanced by the drugs. In vivo a transient shortening of the response could be seen. 26-34 h after bilateral extirpation of the pelvic ganglia there was prominent degeneration activity in the bladders in vitro as well as in vivo. Atropine or scopolamine inhibited this activity in vivo but enhanced it in vitro. The neurogenic contractile response to field stimulation of the bladder nerves was blocked in vivo but not in vitro by the antimuscarinic drugs 26-34 h after neurectomy. The results support the concept that the excitatory neurotransmission in the detrusor is essentially cholinergic. An explanation of the difference between the in vivo and the in vitro results based on differences in degree of blockade of pre- and post-junctional muscarinic receptors and diffusion of the antimuscarinics in the tissue is proposed.

Animals↗
PubMed1980

Endometrial cholinergic secretory responses during estrous cycle, pregnancy and after estrogen and/or progesterone treatment of the guinea-pig.

During estrous cycle as well as during pregnancy and after treatment with estrogen and/or progesterone uterine mucus secretory responses were studied as amount of carbohydrate released from everted guinea-pig uteri after transmural nerve stimulation of carbachol administration. In estrous cycle both stimuli increased secretion by about 20% except for the late diestrus phase, when no secretory responses were seen. In pregnancy a secretory response was noted at implantation time. From mid pregnancy and onwards secretory responses of increasing magnitude were obtained. Secretory responses persisted post partum. Evidence of an adrenergic inhibitory influence on the neurogenic cholinergic responses during metestrus was noted. Both stimuli increased carbohydrate release by about 50% above resting level in uteri from animals receiving combined hormone treatment. In uteri of animals receiving estrogen only the increase was about 20%. No definite secretory response was obtained in uteri from animals receiving progesterone only. It is suggested that both hormones are necessary for full cholinergic secretory response to nerve stimulation or muscarinic drugs. It is concluded that muscarinic stimulation of the endometrium results in mucus secretion during all crucial events during the reproductive cycle. Furthermore a cholinergic secretory innervation seems to be present at all these times.

Animals↗
PubMed1979

Evidence for a cholinergic secretory innervation of the guinea-pig endometrium.

Uterine mucus secretion was studied by measuring carbohydrate release from everted guinea-pig uteri placed in organ baths. Field stimulation of the organ resulted in a significant increase in carbohydrate out-put, this increase was inhibited by tetrodotoxin, scopolamine and previous destruction of the paracervical ganglia. Previous section of the hypogastric nerve reduced the response to field stimulation, while interruption of the costouterine connexion or the pelvic nerve was without overt effect. Stimulation of the hypogastric nerve increased uterine carbohydrate secretion. Pelvic nerve stimulation produced no significant effect. Carbachol increased the carbohydrate secretion to the same extent as did field stimulation. Isoprenaline and methoxamine were without significant effect. It is suggested that certain endometrial cells have a cholinergic sympathetic secretory innervation with pre- and postganglionic fibers running in the hypogastric nerve.

Animals↗