ISSN:
1432-2013
Keywords:
Renin
;
Afferent glomerular arteriole
;
Vascular smooth muscle cells
;
Epithelioid cells
;
Junctional transmission
;
Co-transmitter hypothesis
;
Purinergic receptors
;
Angiotensin II
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Intracellular recordings were done in renin-containing juxtaglomerular (JG) and vascular smooth muscle (VSM) cells of the mouse kidney afferent arteriole. Both cell types exhibited a membrane potential around −75 mV and spontaneous depolarizing transients resembling spontaneous excitatory junction potentials (SEJPs) in the arterioles of other organs. The amplitude distribution of these randomly occurring transients was skewed in both cell types with a modal value of 1.2–1.9 mV. Activation of presumably postjunctional α1-, P2-, ANG II- and AVP-receptors depolarized JG and VSM cells. Application of the P1-purinoceptor agonist 2-chloroadenosine strongly increased frequency and amplitude of the SEJP-like events, whereas these transients were abolished by the P1-purinoceptor antagonist 8-phenyltheophylline, both substances presumably acting on prejunctional receptors. The SEJP-like events were completely depressed by reserpine treatment, but not abolished by α1-, α2-, and P2-antagonists. At present, it cannot be decided, whether norepinephrine is the sole transmitter in the afferent arteriole, acting on specialized junctional adrenoceptors with the P2-purinoceptors being irrelevant for junctional transmission, or whether both substances are co-transmitters. Except norepinephrine and ATP, all other transmitter candidates tested were ruled out for various reasons.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00584024
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