Concentration thresholds for fetal swallowing and vasopressin secretion
| Autor: | M. G. Ervin, Y. Fujino, M. G. Ross, Linda Day, C. L. Agnew |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
medicine.medical_specialty
Vasopressin Physiology medicine.medical_treatment Hypertonic Solutions Differential Threshold Thirst Fetus Swallowing Neck Muscles Pregnancy Physiology (medical) Internal medicine medicine Animals Urea Saline Saline Solution Hypertonic Sheep business.industry Osmolar Concentration Deglutition Arginine Vasopressin Plasma osmolality Endocrinology Vasopressin secretion Tonicity Arterial blood Female medicine.symptom business |
| Zdroj: | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 262:R1057-R1063 |
| ISSN: | 1522-1490 0363-6119 |
| DOI: | 10.1152/ajpregu.1992.262.6.r1057 |
| Popis: | In adults, plasma osmolality thresholds for hypernatremia-induced arginine vasopressin (AVP) secretion are similar or less than thresholds for stimulation of thirst. In the fetus, the thresholds for swallowing stimulation and AVP secretion have not been defined. Fetal swallowing and AVP secretory responses to hypertonic NaCl and urea were determined in six fetuses (130 +/- 1 1 days) chronically prepared with thyrohyoid, nuchal and thoracic esophagus, and diaphragm electromyograms (EMG), an esophageal flow probe, and vascular catheters. Fetuses received intracarotid injections (0.15 ml/kg) of increasing concentrations of NaCl (0.15, 0.30, 0.45, 0.60, 0.75, and 0.90 M), administered at 2-min intervals. A swallow was defined as a coordinated time-sequence of fetal thyrohyoid, nuchal esophagus, and thoracic esophagus EMG activity. The threshold saline concentration for swallowing was defined as the minimum NaCl dose eliciting swallow responses (within 20 s) after four of five injections at each dose. During a 2-h control period swallowing averaged 25.0 +/- 10.1 ml/h and 39.4 +/- 14.6 swallows/h. The mean NaCl threshold concentration for swallowing stimulation was 0.56 +/- 0.06 M. Fetal plasma AVP (2.6 +/- 0.9 pg/ml) increased significantly at the maximum subthreshold (7.6 +/- 4.0 pg/ml) and the threshold NaCl concentration (8.2 +/- 4.0 pg/ml) that stimulated swallowing. On a subsequent day, equiosmolar urea injections increased plasma AVP (from 2.2 +/- 0.7 to 7.6 +/- 2.6 pg/ml) but had no effect on swallowing activity. Fetal mean arterial blood pressure increased after injections of threshold saline and urea concentrations. Fetal arterial blood osmolality and sodium concentration did not change during any study.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
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