Figure 2.

Microinjection of Sr²⁺ induced hyperpolarizations. A, With 0.5 mm SrCl₂ inside the injection pipette and small injection rates (about 10 pL/min) repetitive transient hyperpolarizations were induced as long as pressure was applied (small syringes on top indicate the duration of pressure application). B, SrCl₂ (1 mm) inside the injection pipette and larger injection rates (about 50 pL/min) resulted in a nearly permanent hyperpolarization as long as pressure was applied (duration indicated by the small syringe above). When a Sr²⁺ injection was followed by the external perfusion of 1 mm SrCl₂ (duration indicated by white bar), repetitive transient hyperpolarizations were observed. During long-lasting microinjection experiments, a continuous depolarization of the plasma membrane was frequently observed. The membrane potential was registered continuously.