Changes in Smooth Muscle Tone During Osmotic Challenge in Relation to Epithelial Bioelectric Events in Guinea Pig Isolated Trachea

Details

• Personal Author:
  Dortch-Carnes J ; Fedan, Jeffery S. ; Van Scott MR
• Description:
  The relationship between epithelial bioelectric events and epithelium-dependent relaxant and contractile responses of airway smooth muscle in response to hyperosmolar and hypo-osmolar solutions was investigated in guinea pig isolated trachea. Tracheae were perfused with normal or nonisosmotic modified Krebs-Henseleit solution while simultaneously monitoring transepithelial potential difference (VT) and contractile and relaxant responses of the muscle. Baseline VT was 10.1 to 13.3 mV (distal and proximal ends, respectively). Intraluminal amiloride (104 M) induced a 3.7-mV depolarization, verifying that the VT was of epithelial origin. Extraluminal methacholine (3 X 10(-7) M; EC50) caused hyperpolarization and smooth muscle contraction; intraluminal methacholine had very little effect. Increasing intraluminal bath osmolarity via addition of 240 mOsM NaCl or KCl caused an immediate and prolonged depolarization and epithelium-dependent relaxation. Increasing intraluminal bath osmolarity with sucrose evoked similar responses, except that an immediate, transient hyperpolarization and contraction preceded the depolarization and relaxation. Increasing extraluminal bath osmolarity with 240 mOsM NaCl induced depolarization and a longer lasting epithelium-dependent relaxation, whereas extraluminally added 240 mOsM KCl induced a complex smooth muscle response (i.e., transient relaxation followed by contraction), which was accompanied by prolonged depolarization. Intraluminal hypo-osmolarity produced a transient hyperpolarization followed by depolarization along with contraction of the smooth muscle. Bioelectric responses always preceded smooth muscle responses. These results suggest that bioelectric events in the epithelium triggered by nonisosmotic solutions are associated with epithelium-dependent responses in tracheal smooth muscle. [Description provided by NIOSH]
• Subjects:
  Asthma Asthma, Occupational Laboratories Occupational Health Respiratory Tract Diseases Safety
• Keywords:
  Bioelectric-effects Epithelial Laboratory-animals Pulmonary-system-disorders Respiratory Trachea
• ISSN:
  0022-3565
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  North Carolina ; OSHA Region 3 ; OSHA Region 4 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  289
• Issue:
  2
• NIOSHTIC Number:
  nn:20000955
• Citation:
  J Pharmacol Exp Ther 1999 May; 289(2):911-917
• Email:
  jsf2@cdc.gov
• Federal Fiscal Year:
  1999
• Peer Reviewed:
  True
• Source Full Name:
  Journal of Pharmacology and Experimental Therapeutics
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:fb553adcea2a68d2ccbd0f6bb77d002c6c463e19a1400be0e7267d83de2a71aaaa561b9f576c898b3a2879c559fa7dc1d4776ef95aea80ad211f673d784e39fb
• Download URL:
  https://stacks.cdc.gov/view/cdc/198269/cdc_198269_DS1.pdf
• File Type:
  [PDF - 273.01 KB ]