Regenerative electrical activity and arterial contraction in hypertensive rats

Fred S. Lamb, R. Clinton Webb

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

Isolated tail arteries from spontaneously hypertensive rats-stroke prone strain (SHRSP) display oscillatory contractile responses to norepinephrine. These oscillations are not observed in tail arteries from normotensive Wistar-Kyoto rats (WKY). The mechanism underlying these oscillatory contractions was investigated by simultaneous measurement of isometric force development and membrane potential (Em) from tail artery strips in vitro. After equilibration in physiological salt solution containing 1.6 mM calcium (37° C), resting Em was not different between WKY (−52±1.1 mV) and SHRSP (−52±0.4 mV). Norepinephrine (3×10−7 M) produced a similar degree of depolarization in tissues from the two strains (WKY=−42.5±0.9, SHRSP=−41±0.8). However, while Em recordings from WKY arteries were quiescent, those from SHRSP displayed bursts of electrical spiking activity that were temporally associated with the rising phase of oscillations in contractile force. The frequency and duration of these bursts of action potentials increased with the concentration of norepinephrine. Action potentials were not observed in calcium-free solution or in the presence of nifedipine (3×10−7 M). Releasing the passive stretch on the tissues caused a decrease in the rate of spiking. These studies demonstrate catecholamine-induced regenerative electrical activity in tail arteries from SHRSP that is dependent on extracellular calcium. This activity is unique to tail arteries from this strain.

Original languageEnglish (US)
Pages (from-to)70-76
Number of pages7
JournalHypertension
Volume13
Issue number1
DOIs
StatePublished - Jan 1989
Externally publishedYes

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Keywords

  • Membrane potential
  • Nifedipine
  • Norepinephrine
  • Stroke-prone spontaneously hypertensive rats
  • Tail artery

ASJC Scopus subject areas

  • Internal Medicine

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