Adverse effects of artificial buffers on contractile responses of arterial and venous smooth muscle

Br J Pharmacol. 1980 Jun;69(2):207-14. doi: 10.1111/j.1476-5381.1980.tb07892.x.

Abstract

1 In vitro studies were undertaken on rat aortic strips and portal vein segments in order to determine whether or not several commonly used artificial buffers, i.e., tris(hydroxymethyl) aminomethane (Tris), N-2-hydroxyethylpiperazine-N'-2-ethanesulphonic acid (HEPES), morpholine propanesulphonic acid (MOPS), N,N bis(2-hydroxyethyl) glycine (BICINE) and 1,4-piperazinediethanesulphonic acid (PIPES), can exert direct actions on vascular smooth muscle. 2 All artificial buffers used in 5 mM concentrations were found to inhibit development of spontaneous mechanical activity. 3 Tris, HEPES, MOPS, BICINE and PIPES markedly attenuated contractions induced by adrenaline, angiotensin and KCl. The fast phase components of the agonist-induced contractions were either obliterated or reduced in the presence of the artificial buffers. The sustained slow phase components were greatly reduced and retarded by the artificial buffers. 4 The relative order of artificial buffer potency (i.e., from 100% to 14% inhibition) seems to depend upon the agonist and type of smooth muscle. 5 All of these inhibitory effects were reversible, since normal contractile responses and spontaneous mechanical activity could be obtained by simply reincubating the smooth muscles in Krebs-Ringer bicarbonate buffer. 6 A variety of pharmacological antagonists failed to mimic or affect the inhibitory effects of Tris, HEPES, MOPS, PIPES and BICINE. 7 These data show that five of the most commonly used artificial buffers, to study muscles in vitro, exert adverse effects on contractility of arterial and venous smooth muscle.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alkanesulfonates / pharmacology
  • Angiotensin II / pharmacology
  • Animals
  • Buffers
  • Calcium / metabolism
  • Epinephrine / pharmacology
  • Glycine / analogs & derivatives*
  • Glycine / pharmacology
  • HEPES / pharmacology*
  • In Vitro Techniques
  • Male
  • Morpholines / pharmacology*
  • Muscle Contraction / drug effects*
  • Muscle, Smooth, Vascular / physiology*
  • Piperazines / pharmacology*
  • Potassium Chloride / pharmacology
  • Rats
  • Tromethamine / pharmacology*

Substances

  • Alkanesulfonates
  • Buffers
  • Morpholines
  • Piperazines
  • Tromethamine
  • Angiotensin II
  • N,N-bis(2-hydroxyethyl)glycine
  • morpholinopropane sulfonic acid
  • Potassium Chloride
  • HEPES
  • Calcium
  • Glycine
  • Epinephrine